JMA reported 44 events at Showa Crater (at Aira Caldera’s Sakurajima volcano) during 10-14 August, one of which was explosive. Material was ejected as high as 500 m and as far as 300 m. Ash plumes rose as high as 1.8 km above the crater rim. The Alert Level remained at 3 (on a 5-level scale).

Sakurajima volcano at Aira caldera in southernmost Japan has records of historical eruptions back to the 8th century; it was very active in 2012 and 2013, and eruptive activity continued during 2014 with explosions and pyroclastic flows that have been ongoing since 1955. The Showa crater near the summit returned to activity in 2006 and has been the primary active vent since that time. The Japan Meteorological Agency (JMA) provides monthly reports on activity, and the Tokyo VAAC (Volcanic Ash Advisory Center) issued hundreds of reports about ash plumes during 2014.

JMA reported that Showa Crater erupted 471 times in 2014 (figure 46). This is less than half of the 1,097 eruptions reported for 2013, and is lower than average compared with the previous five years, but is also consistent with the periodic variation in eruptive frequency observed between 2009 and 2014 (figure 47).

Figure 46. Number of eruptions during 2014 from Showa Crater on Sakurajima volcano at Aira caldera. Data from JMA Monthly reports.

Figure 47. Number of monthly eruptions at Showa crater (red bars, top) on Sakurajima volcano at Aira caldera between 1 January 2009 and 31 January 2014. The lower graph represents the change in tilt observed with a water-tube tiltmeter at Arimura Station from January 2009 through January 2014 with tidal response eliminated. Inflation of the summit corresponds to positive tilts. Tilt values remained stable and changed little through 2014. Courtesy of JMA (Monthly Summary, January 2014).

Small pyroclastic flows that reached 400-600 m SE or E of Showa Crater were reported three times in 2014, on 22 January, 12 February, and 4 July. The Minamidake summit crater was generally quiet. Only one very small eruption was reported from it on 19 January, and a few very small eruptions were reported there in May. Incandescence was visible from the Showa crater, where virtually all the activity was focused, during several nights almost every week throughout the year.

Significant ashfall was reported by JMA for the 22 January eruption; the Central Fire Department of Kagoshima Fire Prevention Bureau reported that lapilli with a diameter of up to 1 cm fell on an area of Arimuracho in Kagoshima City (about 3 km S of the Showa crater) and larger lapilli with a diameter of 3 cm fell on the Arimura Observation Point (also about 3 km S of the Showa crater).

Most of the explosions during the year sent rocks to within 800 m of the Showa crater. Rocks were ejected as far as 1,300 m from the Showa crater in seven explosive eruptions in January, 12 times in February, 22 times in August, and eight times in October. Larger eruptions sent rocks even farther to distances up to 1,800 m from the crater on 9 March, twice in September, on 28 November, and on 8 and 11 December.

Ash plumes rising to an altitude of 2-3 km were reported weekly by Tokyo VAAC throughout the year. Most of the plumes drifted SE or S, but occasionally were observed drifting NE and other directions as well. Every month (except April) plumes also rose to heights of 3.7-4.6 km, and twice (in May and June) the highest plumes to 5.5 km were reported. A web camera in Tarumizu (12 km SE of Sakurajima) captured a typical ash plume on 24 October that rose to 4.6 km and drifted E (figure 48).

Figure 48. Image from an unspecified webcam in Tarumizu, 12 km SE of Aira's Sakurajima volcano, of an eruption at 1211 local time on 24 October 2014. The ash plume rose to 4.6 km altitude and drifted E. Image archived by and courtesy of Volcano Discovery.

JMA reported 44 events at Showa Crater (at Aira Caldera’s Sakurajima volcano) during 10-14 August, one of which was explosive. Material was ejected as high as 500 m and as far as 300 m. Ash plumes rose as high as 1.8 km above the crater rim. The Alert Level remained at 3 (on a 5-level scale).

JMA reported that events at Showa Crater (at Aira Caldera’s Sakurajima volcano) at 1811 and 1904 on 27 June generated ash plumes that rose 1 km above the crater rim. Weak incandescence from the crater was noted on 30 June. During 30 June-3 July there were five events, one of which was explosive. Material was ejected as far away as 500 m from the crater. The Alert Level remained at 3 (on a 5-level scale).

JMA reported that an event at Showa Crater (at Aira Caldera’s Sakurajima volcano) at 1208 on 15 June generated an ash plume that rose 2.8 km above the crater rim. The Alert Level remained at 3 (on a 5-level scale).

JMA reported four events at Showa Crater (at Aira Caldera’s Sakurajima volcano) during 5-12 June, one of which was explosive. Material was ejected 800 m away the crater rim. Ash plumes rose as high as 3.2 km on 6 June and 1.9 km on 10 June. A very small event occurred at Minamidake summit crater on 5 June. The Alert Level remained at 3 (on a 5-level scale).

JMA reported 15 events at Showa Crater (at Aira Caldera’s Sakurajima volcano) during 22-29 May, two of which were explosive. Material was ejected as high as 800 m above the crater rim. Ash plumes rose as high as 3.4 km on 31 May and 3 km on 2 June. Very small events occurred at Minamidake summit crater during 4-5 June. The Alert Level remained at 3 (on a 5-level scale).

JMA reported 22 events at Showa Crater (at Aira Caldera’s Sakurajima volcano) during 22-29 May, seven of which were explosive. The explosions ejected material as high as 800 m above the crater rim, and as far away as 500 m. Ash plumes rose as high as 3.3 km on 23 May and 3.4 km on 29 May. Crater incandescence was detected on 25 May. A very small event occurred at Minamidake summit crater on 26 May. The Alert Level remained at 3 (on a 5-level scale).

JMA reported that 10 events at Showa Crater (at Aira Caldera’s Sakurajima volcano) were detected during 15-18 May. One of the events, an explosion at 2302 on 17 May, generated a large ash plume that rose 3 km above the crater rim and ejected material 500-800 m from the crater. That same day at 1526 an explosion at Minamidake summit crater produced an ash plume that rose 1.1 km above the crater. At 0058 on 19 May a plume rose 1.4 km above Showa Crater's rim. Very small events occasionally occurred at Minamidake summit crater during 19-22 May. The Alert Level remained at 3 (on a 5-level scale).

According to JMA, fieldwork at Aira Caldera’s Sakurajima volcano revealed that the sulfur dioxide flux rose from 300 tons on 28 April to 1,700 tons on 8 May; the last time sulfur dioxide flux was above 1,000 tons was 23 June 2015. At 1312 on 12 May an explosion at Showa Crater generated a plume that rose 700 m above the crater rim, into a weather cloud. Four events were detected during 13-15 May; one of the events, an explosion at Showa Crater on 14 May, produced a plume that rose 2.3 km above the crater rim. The Alert Level remained at 3 (on a 5-level scale).

JMA reported that nine events at Showa Crater (at Aira Caldera’s Sakurajima volcano) were detected during 1-8 May. One of the events was explosive, generating an ash plume that rose 4 km above the crater rim and ejecting material 300-500 m from the crater. Ashfall was reported in the cities of Kagoshima (3 km NW), Hioki (25 km WNW), and Ichikikushikino (40 km NW). Nighttime crater incandescence was noted on 2 and 5 May. An event at 1213 on 5 May at Minamidake summit crater produced a plume that rose 500 m above the crater rim. The Alert Level remained at 3 (on a 5-level scale).

JMA reported that there were less than 10 small events at Showa Crater (at Aira Caldera’s Sakurajima volcano) during 26-27 April, the first eruptions at that crater since 26 July 2016. During 28 April-1 May there were 16 events, of which two were explosive, ejecting tephra up to 800 m from the crater. One of the explosive events, at 1101 on 28 April, generated an ash plume that rose 3.2 km above the crater rim. The Alert Level remained at 3 (on a 5-level scale).

JMA reported that an explosion from the Minamidake summit crater (at Aira Caldera’s Sakurajima volcano) at 1004 on 4 April generated an ash plume that rose 1.2 km above the crater rim. During field work later that day, scientists observed ashfall in Sakurajima Koike-cho in Kagoshima (3 km NW). The Alert Level remained at 3 (on a 5-level scale).

JMA reported very small eruptions at Minamidake summit crater (at Aira Caldera’s Sakurajima volcano) during 28-29 March. Based on JMA notices and satellite-image analyses, the Tokyo VAAC reported that on 4 April an ash plume rose to an altitude of 8 km (26,200 ft) a.s.l. and drifted W. The Alert Level remained at 3 (on a 5-level scale).

JMA reported that an explosion at Minamidake summit crater (at Aira Caldera’s Sakurajima volcano) detected at 1803 on 25 March generated a pyroclastic flow that traveled 1.1 km down the S flank. An explosion at 2228 produced an ash plume that rose 1.4 km above the crater rim. Ash fell in the vicinity of the volcano and as far as 4.5 km E. Based on JMA notices and satellite-image analyses, the Tokyo VAAC reported that ash plumes drifted SE and E that same day.

JMA reported that on 4 August a small-scale explosion occurred at Minamidake summit crater (at Aira Caldera’s Sakurajima volcano) ejecting material as high as 400 m above the crater rim. The Alert Level remained at 3 (on a 5-level scale).

JMA reported that on 26 July an explosive eruption at Showa Crater (at Aira Caldera’s Sakurajima volcano) ejected tephra 800 m away from the crater and generated an ash plume that rose 5 km above the crater rim. Significant amounts of ash fell in the W and SW parts of the island and in multiple areas of Kagoshima (10-12 km W). The Alert Level remained at 3 (on a 5-level scale).

JMA reported that a small-scale explosion at Showa Crater (at Aira Caldera’s Sakurajima volcano) occurred at 1336 on 29 June. An explosion at 0413 on 2 July generated an ash plume that rose 1.2 km above the crater rim, and ejected tephra as far as 800 m from the crater. The Alert Level remained at 3 (on a 5-level scale).

JMA reported that an explosion at the Minamidake summit crater (at Aira Caldera’s Sakurajima volcano) generated an ash plume that rose 3.7 km above the crater rim. During 13-16 May explosions from Showa Crater generated an ash plume that rose as high as 3.5 km above the crater rim. On 13 May the Alert Level remained at 3 (on a 5-level scale).

JMA reported that on 8 May explosions from Showa Crater (at Aira Caldera’s Sakurajima volcano) generated an ash plume that rose 3.3 km above the crater rim and ejected tephra as far as 1.3 km from the crater. The Alert Level remained at 3 (on a 5-level scale).

JMA reported that during 11-15 April the seismic network at Aira Caldera’s Sakurajima volcano detected seven eruptions at Showa Crater. An event at 1924 on 17 April generated an ash plume that rose 2.2 km above the crater rim. The Alert Level remained at 3 (on a 5-level scale).

JMA reported that during 4-8 April the seismic network at Aira Caldera’s Sakurajima volcano detected four explosions at Showa Crater, generating ash plumes that rose as high as 3.5 km above the crater rim. One of the explosions, recorded at 1333 on 6 April, produced an ash plume that rose 3.5 km. An explosion at 1922 on 8 April generated an ash plume that rose 3.7 km and ejected cinders as far as 1.3 km away. Small-scale explosions occurred at Minamidake summit crater on 5, 6, and 9 April. The Alert Level remained at 3 (on a 5-level scale).

JMA reported that on 1 April an explosion at Aira Caldera’s Sakurajima volcano generated an ash plume that rose 2 km above Showa's crater rim. An explosion at Minamidake summit crater also produced an ash plume which rose 800 m above its crater rim. Three of five explosions detected at Showa during 1-4 April generated ash plumes that rose as high as 3.5 km, and ejected tephra as far as 1,300 m. Reports of falling tephra, 2 cm in diameter, came from a town 3 km away. At 0608 on 3 April an ash plume from an explosion rose 700 m above Minamidake. The Alert Level remained at 3 (on a 5-level scale).

JMA reported that an explosion at 0159 on 24 March from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 800 m, and generated an ash plume that rose 2.1 km above the crater rim. At 0825 on 25 March an explosion at Minamidake summit crater produced an ash plume that rose 2 km above the crater rim. Two explosions at Showa Crater, detected at 0248 and 1044 on 26 March, sent ash plumes as high as 2.7 km and ejected tephra 1.3 km away onto the flanks. Tephra 8 mm in diameter fell 4 km away. Ash from an explosion at Minamidake rose as high as 2 km. The Alert Level remained at 3 (on a 5-level scale).

JMA reported that at 1820 on 8 March an explosion from Minamidake Crater at Aira Caldera’s Sakurajima volcano generated a plume that rose 1.9 km above the crater rim. During an overflight on 11 March scientists observed a white plume rising 500 m above Minamidake. Later that day, at 2007, an explosion produced a plume that rose 1.7 km.

During 29 February-4 March JMA reported that two explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 500 m. At 0038 on 4 March an explosion at Minamidake summit crater generated an ash plume that rose 1.6 km. The Alert Level remained at 3 (on a 5-level scale).

During 15-22 February JMA reported that six explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m. A small-scale eruption occurred from Minamidake summit crater on 20 February. The Alert Level remained at 3 (on a 5-level scale).

During 15-22 February JMA reported that six explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m. A small-scale eruption occurred from Minamidake summit crater on 20 February. The Alert Level remained at 3 (on a 5-level scale).

During 8-15 February JMA reported that 11 explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m. Based on JMA reports and satellite data, the Tokyo VAAC reported that during 10-12 February ash plumes rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted N, NW, W, S, and SE. On 14 February a pilot observed an ash plume that rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted S. The Alert Level remained at 3 (on a 5-level scale).

JMA reported that an explosive eruption at Showa Crater (at Aira Caldera’s Sakurajima volcano) began at 1856 on 5 February and generated an ash plume that rose 1.3-1.8 km above the crater rim. Lightning was observed in the ash cloud, and incandescent tephra was ejected as far as 1.8 km onto the flanks. The Alert Level was raised to 3 (on a 5-level scale); it had previously been lowered to 2 on 25 November 2015. During an overflight the next day scientists did not see any significant changes to the crater; a plume obscured views of Minamidake summit crater. Sulfur dioxide emissions were 100 tons/day, which was the same level measured on 3 February.

Explosions were detected on 8 February. Based on JMA reports and satellite data, the Tokyo VAAC reported that during 8-9 February ash plumes rose to altitudes of 1.5-3.3 km (5,000-11,000 ft) a.s.l. and drifted E and SE.

JMA reported that during 21-28 September emissions rose from both Showa Crater and Minami-Dake Crater at Aira Caldera’s Sakurajima volcano. An explosion at Minami-Dake Crater at 0233 on 28 September generated a plume that rose 2.7 km above the crater. The Alert Level remained at 3 (on a 5-level scale).

JMA reported that small explosions occasionally occurred at Minamidake Crater at Aira Caldera’s Sakurajima during 14-21 September. On 16 and 18 September an explosion from Showa Crater ejected tephra as far as 800 m, and incandescence from the crater was occasionally visible at night. The Alert Level remained at 3 (on a 5-level scale).

JMA reported 30 explosions during 31 August-7 September from Showa Crater at Aira Caldera’s Sakurajima volcano, some that ejected tephra as far as 1,300 m, and incandescence from the crater that was occasionally visible at night. The Alert Level remained at 3 (on a 5-level scale).

JMA reported that a small-scale explosion from Showa Crater (Aira Caldera’s Sakurajima volcano) occurred on 19 August. In a report from 21 August JMA noted that the possibility of larger-scale eruption had decreased since 15 August. Deformation data during 15-16 August suggested a dike intrusion beneath Minamidake Crater, centered 1-3 km below sea level, with an estimated volume of 2 million cubic meters. Small-scale explosions at Showa Crater occurred on 21 and 23 August. The Alert Level remained at 4 (on a 5-level scale).

On 15 August JMA reported an increase in the frequency of volcanic earthquakes detected under Minami-Dake Crater (Aira Caldera’s Sakurajima volcano) and that inflation became more rapid. This activity suggested an increase in the possibility of larger-scale explosions, prompting JMA to raise the Alert Level to 4 (on a 5-level scale). Elevated activity continued to be detected through 18 August.

JMA reported that during 21-24 July a small-scale, non-explosive event at Showa Crater (Aira Caldera’s Sakurajima volcano) was recorded, and incandescence from the crater was visible on 23 July. An explosion on 25 July ejected tephra as far as 800 m away. The Alert Level remained at 3 (on a 5-level scale).

JMA reported five explosions during 13-21 July from Showa Crater at Aira Caldera’s Sakurajima volcano, some that ejected tephra as far as 500 m, and incandescence from the crater that was occasionally visible. A small-scale eruption occurred from Minami-Dake Crater on 16 July. The Alert Level remained at 3 (on a 5-level scale).

JMA reported that during 6-13 July small-scale explosions occurred at Showa Crater at Aira Caldera’s Sakurajima volcano. One larger explosion ejected ballistics 200-300 m above the crater. Incandescence from the crater was occasionally visible at night. Rumbling was occasionally heard several tens of kilometers away. The Alert Level remained at 3 (on a 5-level scale).

JMA reported 14 explosions during 29 June-6 July from Showa Crater at Aira Caldera’s Sakurajima volcano, some that ejected tephra as far as 1,300 m, and incandescence from the crater that was occasionally visible. The Alert Level remained at 3 (on a 5-level scale).

JMA reported 26 explosions during 22-29 June from Showa Crater at Aira Caldera’s Sakurajima volcano, some that ejected tephra as far as 1,300 m, and incandescence from the crater that was visible during 22-23 and 27 June. A small-scale eruption occurred from Minami-Dake Crater on 22 June. The Alert Level remained at 3 (on a 5-level scale).

JMA reported 15 explosions during 15-22 June from Showa Crater at Aira Caldera’s Sakurajima volcano, some that ejected tephra as far as 800 m, and incandescence from the crater that was occasionally visible at night. The Alert Level remained at 3 (on a 5-level scale).

JMA reported that incandescence from Showa Crater at Aira Caldera’s Sakurajima volcano was visible at night on 13 June. An explosion occurred at 1007 on 15 June but inclement weather prevented visual observations. The Alert Level remained at 3 (on a 5-level scale).

JMA reported 14 explosions during 1-5 June from Showa Crater at Aira Caldera’s Sakurajima volcano, some that ejected tephra as far as 1,300 m, and incandescence from the crater that was occasionally visible at night. Explosive eruptions on 4 June generated small-scale pyroclastic flows that descended the E flank of Showa Crater. The Alert Level remained at 3 (on a 5-level scale).

JMA reported 18 explosions during 25-29 May and 24 during 29 May-1 June from Showa Crater at Aira Caldera’s Sakurajima volcano, some that ejected tephra as far as 1,300 m, and incandescence from the crater was occasionally visible at night. On 29 May and 1 June explosions generated large ash plumes that rose 3.3 km above the crater. The Alert Level remained at 3 (on a 5-level scale).

JMA reported 19 explosions during 18-25 May from Showa Crater at Aira Caldera’s Sakurajima volcano, some that ejected tephra as far as 1,300 m, and incandescence from the crater was occasionally visible at night. During 21-22 May explosions generated ash plumes that rose 3-4.3 km above the crater. The Alert Level remained at 3 (on a 5-level scale).

JMA reported 31 explosions during 11-18 May from Showa Crater at Aira Caldera’s Sakurajima volcano, some that ejected tephra as far as 1,800 m. Incandescence from the crater was visible at night on 11 May. The next day a very small explosion at Minami-Dake Crater generated a 200-m-high plume. Three larger explosions from Showa Crater, at 2104 and 2200 on 13 May, and 0416 on 14 May, generated ash plumes that rose as high as 3.5 km. Tephra, about 2 cm in diameter, and ashfall reported in Kagoshima Kurokami was attributed to the explosion at 2104 on 13 May. During 15-18 May ash plumes rose as high as 3 km twice, except from an explosion at 1732 on 17 May, an event that produced a 3.8-km-high ash plume. The Alert Level remained at 3 (on a 5-level scale).

JMA reported 105 explosions during 1-11 May from Showa Crater at Aira Caldera’s Sakurajima volcano tephra was ejected as far as 1,800 m. Incandescence from the crater was visible at night. Explosions occurred at 2309 on 4 May, and at 1049 and 1126 on 8 May. Sulfur dioxide gas emissions measured during fieldwork conducted on 8 May were 2,300 tons per day (400 tons per day was measured on 16 April). An explosion at 2021 on 10 May generated a large ash plume that rose 3.2 km.

JMA reported that 12 explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m during 27 April-1 May. Incandescence from the crater was visible at night. An explosion at 0720 on 27 April generated a large ash plume that rose 3.5 km above the crater. The next day an explosive eruption was detected by the seismic network for 40 minutes. A very small pyroclastic flow traveled 500 m down the SE flank of Showa Crater. The Alert Level remained at 3 (on a scale of 1-5). Based on JMA notices, the Tokyo VAAC reported that explosions during 29 April-5 May generated plumes which rose to altitudes of 1.8-3.4 km (6,000-11,000 ft) a.s.l. and drifted in multiple directions.

JMA reported that 29 explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m during 20-24 April. Nine of the explosions generated ash plumes that rose 3 km above the crater rim; one explosion, on 24 April, produced an ash plume that rose 4 km. Incandescence from the crater was visible on one night. The Alert Level remained at 3 (on a scale of 1-5). Based on JMA notices, the Tokyo VAAC reported that explosions during 22-28 April generated plumes which rose to altitudes of 1.5-4.9 km (5,000-16,000 ft) a.s.l. and drifted S, SE, E, NE, and N.

JMA reported 23 explosions from Showa Crater at Aira Caldera’s Sakurajima volcano during 13-17 April. Incandescence from the crater was visible at night on 14 April. An explosion at 1355 on 17 April generated a large ash plume that rose 3 km above the crater, and a second explosion ejected tephra as far as 1,800 m. Inflation continued to be detected. The Alert Level remained at 3 (on a scale of 1-5). Based on JMA notices, the Tokyo VAAC reported that explosions during 15-18 and 20-21 April generated plumes which rose to altitudes of 1.2-4.6 km (4,000-15,000 ft) a.s.l. and drifted E and SE.

JMA reported that 15 explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m during 6-10 April. Incandescence from the crater was visible at night on 7 and 9 April, and inflation continued to be detected. The Alert Level remained at 3 (on a scale of 1-5). Based on JMA notices, the Tokyo VAAC reported that explosions during 8-13 April generated plumes which rose to altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l. and drifted in multiple directions. Pilots observed ash plumes that rose to altitudes of 2.1-2.4 km (7,000-8,000 ft) and drifted E and SE during 10-11 April.

JMA reported that 20 explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m during 30 March-3 April. Incandescence from the crater was periodically visible at night, and inflation continued to be detected. The Alert Level remained at 3 (on a scale of 1-5). Based on JMA notices, the Tokyo VAAC reported that explosions during 1-2, 5, and 7 April generated plumes which rose to altitudes of 1.5-3.4 km (5,000-11,000 ft) a.s.l. and drifted E and NE. Pilots observed ash plumes that rose to an altitude of 3 km (10,000 ft) on 1 April and 1.5 km (5,000 ft) a.s.l. on 7 April.

Based on JMA notices, the Tokyo VAAC reported explosions from Aira Caldera’s Sakurajima volcano during 18-25 March; plumes rose to altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l. and drifted S, SE, E, and NE during 18-19 and 21-25 March. JMA reported that 19 explosions from Showa Crater ejected tephra as far as 1,300 m during 20-23 March. Incandescence from the crater was periodically visible at night, and inflation continued to be detected. The Alert Level remained at 3 (on a scale of 1-5).

JMA reported that 10 explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m during 13-16 March. Incandescence from the crater was periodically visible at night, and inflation continued to be detected. The Alert Level remained at 3 (on a scale of 1-5). Based on JMA notices, the Tokyo VAAC reported that during 11-17 March plumes rose to altitudes of 1.8-4.3 km (6,000-14,000 ft) a.s.l. and drifted SE, E, and N.

JMA reported that seven explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m during 2-6 March. Incandescence from the crater was periodically visible at night, and inflation continued to be detected. During a field survey conducted on 4 March scientists observed deposits of tephra, up to 2 cm in diameter, in an area 3 km S of Showa Crater. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that during 4-5 and 7-8 March plumes rose to altitudes of 1.5-3.7 km (5,000-12,000 ft) a.s.l. and drifted in multiple directions.

JMA reported that eight explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m during 23-27 February. An explosion on 24 February generated an ash plume that rose 3.3 km. Incandescence from the crater was visible at night on 25 and 27 February, and inflation continued to be detected. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that during 25-28 February and 2-3 March plumes rose to altitudes of 1.2-3.4 km (4,000-11,000 ft) a.s.l. and drifted N, NE, E, and SE.

JMA reported that 10 explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m during 16-20 February. Incandescence from the crater was visible at night on 19 February, and inflation continued to be detected. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that during 18-24 February plumes rose to altitudes of 1.8-4.6 km (6,000-15,000 ft) a.s.l. and drifted in multiple directions.

JMA reported that 36 explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m during 9-13 February. Incandescence from the crater was visible at night during 9-11 February, and inflation continued to be detected. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that during 11-17 February plumes rose to altitudes of 1.8-3.7 km (6,000-12,000 ft) a.s.l. and drifted E and SE. On 17 February pilots observed ash plumes that rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted SE

The Tokyo VAAC reported that during 28 January-3 February plumes from Aira Caldera’s Sakurajima volcano rose to altitudes of 1.5-3.3 km (5,000-11,000 ft) a.s.l. and drifted NE, E, SE, and S. On 1 February pilots observed ash plumes that rose to altitudes of 2.7-3.3 km (9,000-11,000 ft) a.s.l. JMA reported that nine explosions from Showa Crater ejected tephra as far as 1,800 m during 26-30 January. Incandescence from the crater was visible at night, and inflation continued to be detected. An explosion on 30 January caused tephra fall (2 cm in diameter) in Kagoshima Kurokami (3.5 km E). The Alert Level remained at 3 (on a scale of 1-5).

The Tokyo VAAC reported that during 28 January-3 February plumes from Aira Caldera’s Sakurajima volcano rose to altitudes of 1.5-3.3 km (5,000-11,000 ft) a.s.l. and drifted NE, E, SE, and S. On 1 February pilots observed ash plumes that rose to altitudes of 2.7-3.3 km (9,000-11,000 ft) a.s.l. JMA reported that nine explosions from Showa Crater ejected tephra as far as 1,800 m during 26-30 January. Incandescence from the crater was visible at night, and inflation continued to be detected. An explosion on 30 January caused tephra fall (2 cm in diameter) in Kagoshima Kurokami (3.5 km E). The Alert Level remained at 3 (on a scale of 1-5).

JMA reported that three explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 800 m during 19-23 January. Incandescence from the crater was visible at night on 22 January. Inflation continued to be detected. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that on 23 January plumes rose to altitudes of 3-4.9 km (10,000-16,000 ft) a.s.l. and drifted SE. During 24-27 January plumes rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l. and drifted SE, E, NE, and N.

The Tokyo VAAC reported that during 15 and 17-20 January plumes from Aira Caldera’s Sakurajima volcano rose to altitudes of 1.8-3.4 km (6,000-11,000 ft) a.s.l. and drifted S, SE, and E. The Alert Level remained at 3 (on a scale of 1-5). JMA reported that five explosions from Showa Crater ejected tephra as far as 1,300 m during 16-19 January. Incandescence from the crater was visible at night on 16 January. Inflation continued to be detected. The Alert Level remained at 3 (on a scale of 1-5).

JMA reported that four explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m during 5-9 January. Incandescence from the crater was visible at night during 7-8 January. Inflation continued to be detected. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that during 7-8, 10, and 12-13 January plumes rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l. and drifted SE, SW, and NW. On 8 and 10 January pilots observed ash plumes that rose to altitudes of 1.5 km (10,000 ft) a.s.l. The Alert Level remained at 3 (on a scale of 1-5).

The Tokyo VAAC reported that during 1-6 January plumes from Aira Caldera’s Sakurajima volcano rose to altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l. and drifted SE and S. During 3-5 January pilots observed ash plumes that rose to altitudes of 1.8-4 km (6,000-13,000 ft) a.s.l. On 6 January JMA reported that inflation at Sakurajima had been detected during the previous few days. The Alert Level remained at 3 (on a scale of 1-5).

JMA reported that four explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,800 m during 8-12 December. Incandescence from the crater was visible at night during 11-12 December. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported plumes during 11, 13, and 15-16 December that rose to altitudes of 1.2-3 km (4,000-10,000 ft) a.s.l. and drifted SE and NE. On 11 December a pilot observed an ash plume that rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted NE.

JMA reported that three explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,800 m during 5-8 December. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that during 4 and 6-8 December plumes rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l. and drifted SE and E.

JMA reported that periodic, small-scale explosions from Showa Crater at Aira Caldera’s Sakurajima were detected during 25-28 November. Weak incandescence from the crater was visible during 25-26 November. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that during 27-30 November plumes rose to altitudes of 1.5-4.9 km (5,000-16,000 ft) a.s.l. and drifted NE, E, and SE. An eruption on 2 December generated a plume that rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted SE.

JMA reported that two explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m during 17-21 November. Weak incandescence from the crater was visible during 18-19 November. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that on 19 November an explosion produced a plume that rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted NE. An eruption on 23 November generated a plume that rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted E.

JMA reported that three explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 800 m during 10-14 November. Incandescence from the crater was visible during 12-13 November. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that during 12-17 November plumes rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted E and SE.

JMA reported that nine explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m during 4-7 November. An explosive eruption on 7 November generated an ash plume that rose 3.5 km. An eruption later that day from Minami-Dake Crater produced a plume that rose 1.4 km. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that during 5-8 November plumes rose to altitudes of 2.1-4.6 km (7,000-15,000 ft) a.s.l. and drifted NW, W, E, and SE.

JMA reported that two explosions from Showa Crater at Aira Caldera’s Sakurajima volcano were detected during 20-24 October; an explosion on 24 October generated a plume that rose 3.2 km. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that on 24 October ash plumes rose to altitudes of 3-4.6 km (10,000-15,000 ft) a.s.l. and drifted E. During 25-26 October plumes rose to altitudes of 2.4-2.7 km (8,000-9,000 ft) a.s.l. and drifted E. On 28 October plume rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted S.

JMA reported that three explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m during 14-17 October. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that on 16, 18, and 21 October ash plumes rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l. and drifted S, SE, and NE.

JMA reported that six explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m during 6-10 October. Incandescence from Showa Crater was visible at night. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that during 9-10 October plumes rose to altitudes of 1.5-1.8 km (5,000-6,000 ft) a.s.l. and drifted W.

JMA reported that five explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m from the crater during 29 September-3 October. Incandescence from Showa Crater was visible at night during 2-3 October. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that during 2-7 October plumes rose to altitudes of 1.2-3.7 km (4,000-12,000 ft) a.s.l. and drifted in multiple directions. On 2 October a pilot observed an ash plume that rose to an altitude of 3 km (10,000 ft) a.s.l.

JMA reported that 12 explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m during 26-29 September. Incandescence from Showa Crater was visible at night during 26-27 September. An explosion on 28 September produced a dense ash plume that rose 3 km. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that during 24-30 September plumes rose to altitudes of 1.8-4 km (6,000-13,000 ft) a.s.l. and drifted W, S, SE, and E. On 27 September a pilot observed an ash plume that rose to an altitude of 4.3 km (14,000 ft) a.s.l.

JMA reported that 24 explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m during 16-19 September. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that during 17-23 September plumes rose to altitudes of 1.8-3.4 km (6,000-11,000 ft) a.s.l. and drifted in multiple directions. During 17-18 and 23 September pilots observed ash plumes that rose to altitudes of 2-3 km (7,000-10,000 ft) a.s.l.

During 8-16 September JMA maintained Alert Level 3 for Aira Caldera’s Sakurajima volcano. Volcanic earthquakes and tremor were detected during this time period. There were 12 explosions that ejected tephra up to 1,300 m above Showa crater. Sustained eruptions from the crater were recorded on 10 and 11 September and nighttime incandescence was detected during 11-16 September.

During 10-16 September JMA reported ash eruptions, causing the Tokyo VAAC to issue regular advisories; however, ash was not visible in satellite images.

During 1-9 September JMA maintained Alert Level 3 for Aira Caldera’s Sakurajima volcano. There were 23 explosions recorded from Showa crater from 1 to 4 September; during 5-7 September there were 18 explosions.

During 3-7 September JMA reported ash eruptions, causing the Tokyo VAAC to issue regular advisories; however, ash was not visible in satellite images. At 0437 on 9 September, ash was visible in satellite images and reached 3,300 m (11,000 ft) a.s.l. drifting S.
On 2 and 3 September, ballistics reached 1,300-1,800 m above the crater. Nighttime incandescence was detected during 4-5 September from Showa crater. Volcanic earthquakes and tremor were detected during 1-8 September.

During 27 August-2 September JMA reported 42 explosions from Showa Crater at Aira Caldera’s Sakurajima volcano that ejected ballistics 800-1300 m from the crater. The explosions were accompanied by volcanic earthquakes and volcanic tremor. On 30-31 August clear incandescence was visible by high-sensitivity camera at night, with a “smoke” plume rising 3 km above the crater on the 31st. The Tokyo VAAC reported explosions during 13-17 August with plumes that rose to an altitude of 1.2-4 km (4,000-13,000 ft) a.s.l. and drifted E, NE, N, and SE. The Alert Level remained at 3 (on a scale of 1-5).

During 20-26 August JMA reported 17 explosions from Showa Crater at Aira Caldera’s Sakurajima volcano that were accompanied by volcanic earthquakes and volcanic tremor, and which ejected ballistics 500-800 m away. On 20-24 August clear incandescence was visible using high-sensitivity camera at night. On 20-26 August the Tokyo VAAC reported explosions with plumes that rose to an altitude of 1.2-2.7 km (4,000-9,000 ft) a.s.l. and drifted NE and N, though volcanic ash could not be identified in satellite data. The Alert Level remained at 3 (on a scale of 1-5).

During 11-15 August JMA reported 14 explosions from Showa Crater at Aira Caldera’s Sakurajima volcano that ejected ballistics 800-1300 m away. During 15-18 August were four more explosions with similar ballistic ejections. The explosions were accompanied by volcanic earthquakes and volcanic tremor. On most days faint to clear incandescence was visible using a high-sensitivity camera at night. On 13-17 August the Tokyo VAAC reported explosions with plumes that rose to an altitude of 1.5-3 km (5,000-10,000 ft) a.s.l. and drifted NE and N, though volcanic ash could not be identified in satellite data. The Alert Level remained at 3 (on a scale of 1-5).

JMA reported an explosion from Showa Crater at Aira Caldera’s Sakurajima volcano on 6 August that ejected ballistics 300-500 m from Showa crater and a plume that rose 500 m above the crater. On 10 August three explosions ejected ballistics 500-800 m from Showa crater accompanied by volcanic earthquakes and volcanic tremor. On 6-11 August, incandescence was clearly visible at night by high-sensitivity camera. The Tokyo VAAC reported that plumes from explosions on 6, 8-10 August rose to an altitude of 1.2-2.4 km (4,000-8,000 ft) a.s.l. and drifted NW, N, E, SE, and S. The Alert Level remained at 3 (on a scale of 1-5).

JMA reported an explosion from Showa Crater at Aira Caldera’s Sakurajima volcano on 30 July that ejected ballistics 300-500 m from Showa crater and six other explosions on 31 July accompanied by volcanic earthquakes and volcanic tremor. In general, explosions, volcanic tremor and volcanic earthquakes decreased 1-4 August. On 31 July-4 August, incandescence was clearly visible by high-sensitivity camera at night. The Tokyo VAAC reported that a plume from the 30 July explosion rose to an altitude of 1.2 km (4,000 ft) a.s.l. and drifted NW. The Alert Level remained at 3 (on a scale of 1-5).

JMA reported three explosive eruptions from Showa Crater at Aira Caldera’s Sakurajima volcano on 22, 25, and 27 July that ejected ballistics 300-800 m away. In general, the eruptions were accompanied by volcanic earthquakes and increasing volcanic tremor. On 28 July a very small eruption cloud rose 200 m above Minami-Dake Crater. The Tokyo VAAC reported that on 23, 25, and 27 July plumes rose to an altitude of 1.5-2.5 km (5,000-8,000 ft) a.s.l. and drifted E and NE. The Alert Level remained at 3 (on a scale of 1-5).

JMA reported that seven explosive eruptions from Showa Crater at Aira Caldera’s Sakurajima volcano during 14-22 July ejected ballistics 500-800 m from Showa crater. In general, volcanic earthquakes decreased and tremor increased. The Tokyo VAAC reported that during 16-20 July plumes rose to an altitude of 2-3 km (7,000-10,000 ft) a.s.l. and drifted E and SE; on 22 July a plume rose to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted N. The Alert Level remained at 3 (on a scale of 1-5).

During 11-14 July, JMA reported four large explosions that ejected deposits 800-1,300 m from Showa crater. Volcanic earthquakes decreased and tremor continued. The Tokyo VAAC reported that during 3-14 July plumes rose to altitudes of 2-3 km (7,000-10,000 ft) a.s.l. and drifted NE, SE, and E. The Alert Level remained at 3 (on a scale of 1-5).

JMA reported that during 23-27 June six explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m. During 27-30 June there were four explosions. A significant explosion on 29 June lasted for 17 minutes.The Tokyo VAAC reported that during 25 June-1 July plumes rose to altitudes of 1.2-3.9 km (4,000-13,000 ft) a.s.l. and drifted NW, SE, and E. The Alert Level remained at 3 (on a scale of 1-5).

JMA reported that during 13-23 June, 4-10 explosions occurred each day from Showa Crater at Aira Caldera’s Sakurajima volcano. Tephra ejected from these events landed as far as 1,800 m away. A significant explosion on 19 June lasted for 17 minutes; the plume rose ~3,000 m above the crater rim and tephra was ejected to a distance of 1,300-1,800 m. Field surveys conducted on 12 June determined an SO2 flux of 270 tons/day (previous measurement of 2,300 tons/day was measured on 9 May). During this reporting period there was no activity from Minamidake summit crater.

JMA reported that during 19-23 May two explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra that landed as far as 1,300 m away. Incandescence from the crater was detected at night during 19-20 May. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that on 6 and 9 June plumes rose to altitudes of 2.1-5.5 km (7,000-18,000 ft) a.s.l. Plumes drifted NW on 9 June.

JMA reported that during 19-23 May two explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m. Incandescence from the crater was detected at night during 19-20 May. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that during 23-25 May plumes rose to altitudes of 2.4-4 km (8,000-13,000 ft) a.s.l. and drifted S, SE, and N.

JMA reported that an explosion from Showa Crater at Aira Caldera’s Sakurajima volcano at 2229 on 12 May ejected tephra as far as 1.8 km from the crater and produced a plume that rose 1.6 km above the crater rim. Incandescence from the crater was detected at night during 13-14 May.

JMA reported that a small non-explosive eruption from Showa Crater at Aira Caldera’s Sakurajima volcano occurred during 7-9 May. Incandescence from the crater was detected at night. A very small eruption at Minamidake Crater at 1151 on 8 May produced a plume that rose 400 m above the crater rim. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that during 10 and 12 May plumes rose to altitudes of 2.4-5.5 km (8,000-18,000 ft) a.s.l. and drifted W, SE, and E. On 13 May a pilot observed an ash plume that rose to an altitude of 1.2 km (4,000 ft) a.s.l.

JMA reported that during 28 April-2 May four explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 500 m. Incandescence from the crater was detected at night during 28-30 April. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that during 30 April-3 May and on 5 May plumes rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l. and drifted E, SE, and SW. On 30 April a pilot observed an ash plume that rose to an altitude of 2.7 km (9,000 ft) a.s.l.

JMA reported that seven explosions from Showa Crater at Aira Caldera’s Sakurajima volcano during 22-25 April ejected tephra as far as 1,300 m. Incandescence from the crater was detected at night. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that during 23-24 and 26 April plumes rose to altitudes of 2.1-3 km (7,000-10,000 ft) a.s.l. and drifted NW, W, and SE. On 26 April a pilot observed an ash plume that rose to an altitude of 2.7 km (9,000 ft) a.s.l. and drifted WNW. An explosion was reported on 29 April.

JMA reported that during 7-11 April two explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 800 m. Incandescence from the crater was detected during the night of 10 April. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that on 10 and 12 April plumes rose to an altitude of 2.4 km (8,000 ft) a.s.l. Plumes drifted SE on 10 April.

JMA reported that during 31 March-4 April two explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m. Incandescence from the crater was occasionally detected at night. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that. During 2 and 5-7 April plumes rose to altitudes of 1.5-2.4 km (5,000-8,000 ft) a.s.l. and drifted SW, S, SE, and E.

JMA reported that 20 explosions from Showa Crater at Aira Caldera’s Sakurajima volcano during 24-28 March ejected tephra as far as 1,300 m. Incandescence from the crater was detected at night on 25 March. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported an explosion on 26 March. During 27-29 March plumes rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted SE, N, and NW.

JMA reported that during 17-20 March five explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m. Incandescence from the crater was detected at night during 17-18 March. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that during 20-25 March plumes rose to altitudes of 1.2-2.7 km (4,000-9,000 ft) a.s.l. and drifted SE, SW, N, and NE.

JMA reported that during 10-14 March two explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m. Incandescence from the crater was detected at night. Volcanologists conducting a field survey on 10 March noted that sulfur dioxide emissions were 190 tons per day, lower than the 1,900 tons per day they measured on 4 March. The Alert Level remained at 3 (on a scale of 1-5).

JMA reported that during 3-7 March six explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m. Incandescence from the crater was detected at night. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported explosions during 5-11 March. Plumes rose to altitudes of 1.2-3 km (4,000-10,000 ft) a.s.l. and drifted NE, E, SE, and S. Pilots observed ash drifting SE at an altitude of 2.1 km (7,000 ft) a.s.l. on 6 March, SE at an altitude of 3.7 km (12,000 ft) a.s.l. on 9 March, and NE at an altitude of 2.7 km (9,000 ft) a.s.l. on 11 March.

JMA reported that during 24-28 February two explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m. Incandescence from the crater was detected during 24-26 February. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported explosions during 27-28 February and 2-4 March. Plumes rose to altitudes of 1.2-4 km (4,000-13,000 ft) a.s.l. and drifted W, NW, NE, SE, and S during 28 February and 2-4 March. A pilot observed ash drifting at an altitude of 1.5 km (5,000 ft) a.s.l. on 2 March.

JMA reported that during 17-21 February three explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that explosions during 19-20 and 22-25 February generated ash plumes that rose to altitudes of 1.8-3.7 km (6,000-12,000 ft) a.s.l. and drifted NE, SE, and S. A pilot observed ash on 20 February.

The Tokyo VAAC reported that explosions during 12-18 February from Aira Caldera’s Sakurajima volcano generated ash plumes on most days that rose to altitudes of 1.5-3.7 km (5,000-12,000 ft) a.s.l. and drifted E, NE, and N. On 12 February a pilot observed an ash plume drifting E at an altitude of 3 km (10,000 ft) a.s.l. JMA reported that during 14-17 February two explosions from Showa Crater ejected tephra as far as 800 m. The Alert Level remained at 3 (on a scale of 1-5).

JMA reported that during 3-7 February five explosions from Sakurajima's Showa Crater ejected tephra as far as 1,300 m. Incandescence from the crater was detected at night. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported explosions during 6, 8-9, and 11 February. On 8 February a pilot observed an ash plume drifting at an altitude of 2.1 km (7,000 ft) a.s.l. Ash plumes rose to an altitude of 1.8 km (6,000 ft) a.s.l. on 9 February and 2.1 (7,000 ft) a.s.l. on 11 February.

JMA reported that during 27-31 January five explosions from Sakurajima's Showa Crater ejected tephra as far as 1,300 m. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that on 29 January and during 31 January-2 February and on 4 February ash plumes rose to altitudes of 1.5-4.9 km (5,000-12,000 ft) a.s.l. and drifted N, NE, and E.

JMA reported that during 20-24 January three explosions from Sakurajima's Showa Crater ejected tephra as far as 1,300 m. An explosion on 22 January generated a small pyroclastic flow that traveled 500 m SE, and tephrafall to the S. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that on 22 January a plume rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted S. That same day pilots observed ash plumes that rose to altitudes of 3.7-4.9 km (12,000-16,000 ft) a.s.l. and drifted S and ESE. On 24 January a pilot observed an ash plume drifting NE at an altitude of 1.2 km (4,000 ft) a.s.l.

JMA reported that during 6-10 January two explosions from Sakurajima's Showa Crater ejected tephra as far as 1,300 m. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that an explosion on 9 January generated a plume that rose to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted SE. A pilot observed an ash plume drifting SE on 14 January.

JMA reported that during 30 December 2013-6 January 2014 no explosions occurred from Sakura-jima's Showa Crater; weak incandescence from the crater was visible at night during 30-31 December. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that an explosion on 7 January generated a plume that rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted E.

JMA reported that on 19 December an explosion from Sakura-jima's Showa Crater ejected tephra as far as 1,300 m. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that during 18-19 and 21-23 December explosions generated plumes that rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l. and drifted E, SE, and S.

The Tokyo VAAC reported that during 11-17 December explosions at Sakura-jima generated plumes that rose to altitudes of 1.2-3.4 km (4,000-11,000 ft) a.s.l. and drifted E, SE, and S. JMA reported that six explosions from Showa Crater ejected tephra as far as 1,800 m during 13-16 December. A six-minute-long explosion was detected on 14 December. The Alert Level remained at 3 (on a scale of 1-5).

The Tokyo VAAC reported that during 4-8 December explosions at Sakura-jima generated plumes that rose to altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l. and drifted E and SE. JMA reported that six explosions from Showa Crater ejected tephra as far as 1,300 m during 6-9 December. Incandescence from the crater was occasionally detected. The Alert Level remained at 3 (on a scale of 1-5).

JMA reported that three explosions from Sakura-jima's Showa Crater ejected tephra as far as 800 m during 29 November-2 December. On 29 November an explosion ejected tephra, up to 1 cm in diameter, 4 km away. The Alert Level remained at 3 (on a scale of 1-5).The Tokyo VAAC reported that during 29-30 November, and 1 and 4 December, explosions generated plumes that rose to altitudes of 2.1-2.7 km (7,000-9,000 ft) a.s.l. and drifted E and SE.

JMA reported that five explosions from Sakura-jima's Showa Crater ejected tephra as far as 800 m during 18-22 November. Incandescence was occasionally detected by a high resolution camera at night. A very small eruption from Minami-dake Crater occurred on 22 November, producing an ash plume that rose 100 m. The Alert Level remained at 3 (on a scale of 1-5).

The Tokyo VAAC reported that during 20-21 and 23-26 November, explosions generated plumes that rose to altitudes of 1.2-4.9 km (4,000-16,000 ft) a.s.l. and drifted N, E, and SE.

The Tokyo VAAC reported that during 6-8 and 10-11 November, explosions from Sakura-jima generated plumes that rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l. and drifted N, NE, E, and SE. On 8 November a pilot observed an ash plume drifting at an altitude of 2.1 km (7,000 ft) a.s.l.

JMA reported that seven explosions from Showa Crater ejected tephra as far as 1,800 m during 1-5 November. On 4 and 5 November, incandescence was detected by a high resolution camera at night. The Alert Level remained at 3 (on a scale of 1-5).

Based on information from JMA, the Tokyo VAAC reported that during 24-29 October explosions from Sakura-jima generated plumes that rose to altitudes of 1.8-4.6 km (6,000-15,000 ft) a.s.l. Plumes rose vertically or drifted N, NW, S, and SE. On 29 October a pilot observed an ash plume drifting SE at an altitude of 2.1 km (7,000 ft) a.s.l.

JMA reported that seven explosions from Sakura-jima's Showa Crater ejected tephra as far as 1,300 m during 15-18 October. An explosion on 15 October was followed by 3-cm-sized tephra falling in areas 3.5 km SW. Based on information from JMA, the Tokyo VAAC reported that during 16-22 October explosions generated plumes that rose to altitudes of 1.2-3.7 km (4,000-12,000 ft) a.s.l. and drifted W, SW, S, and SE. On 21 October an ash plume rose vertically to an altitude of 5.5 km (18,000 ft) a.s.l.

JMA reported that 18 explosions from Sakura-jima's Showa Crater ejected tephra as far as 1,300 m during 17-20 September. Incandescence from the crater was visible some nights. Based on information from JMA and pilot observations, the Tokyo VAAC reported that during 18-20 and 22-23 September explosions generated plumes that rose to altitudes of 1.8-4.6 km (6,000-15,000 ft) a.s.l., and drifted SW, W, and NW.

JMA reported that 16 explosions from Sakura-jima's Showa Crater ejected tephra as far as 1,300 m during 9-13 September. Incandescence from the crater was visible some nights. An explosion at 1326 on 12 September generated an ash plume that rose 3.3 km.

Based on information from JMA, the Tokyo VAAC reported that during 11-18 September explosions generated plumes that rose to altitudes of 1.8-4.3 km (6,000-14,000 ft) a.s.l., and drifted in multiple directions on most days. On 12 and 14 September pilots observed ash plumes that rose to an altitude of 4 km (13,000 ft) a.s.l., and drifted SE and W, respectively.

JMA reported that 15 explosions from Sakura-jima's Showa Crater ejected tephra as far as 1,300 m during 2-6 September. Incandescence from the crater was visible some nights. An explosion at 1100 on 4 September generated an ash plume that rose 2.8 km and drifted S, causing ashfall in areas downwind including Arimuracho (4 km SSE). Tephra 4 cm in diameter was confirmed in an area 3 km S, and tephra 1 cm in diameter was reported 10 km SSE.

Based on information from JMA, the Tokyo VAAC reported that during 4-10 September explosions generated plumes that rose to altitudes of 2.4-4.3 km (8,000-14,000 ft) a.s.l., and most days drifted N, NE, E, S, and SW. On 6 and 8 September pilots observed ash plumes that rose to altitudes of 3-4.6 km (15,000 ft) a.s.l.; plumes drifted NE on 8 September.

JMA reported that 34 explosions from Sakura-jima's Showa Crater ejected tephra as far as 1,300 m during 26-30 August. Incandescence from the crater was visible at night on 26 August. An explosion on 29 August at 0927 generated an ash plume that rose 3 km and caused ashfall in areas from Miyazaki (80 km NW) to Kagoshima (12 km W). Tephra 1 cm in diameter was confirmed in an area 4 km E.

Based on information from JMA, the Tokyo VAAC reported that during 28 August-3 September explosions generated plumes most days that rose to altitudes of 1.5-4 km (5,000-13,000 ft) a.s.l. and drifted E, NE, and NW. On 31 August a pilot observed an ash plume that rose to an altitude of 2.7 km (9,000 ft) a.s.l. and traveled NE.

Based on information from JMA, the Tokyo VAAC reported that during 21-27 August explosions from Sakura-jima generated plumes that rose to altitudes of 1.2-3.4 km (4,000-11,000 ft) a.s.l. and drifted in multiple directions. During 24 and 26-27 August pilots observed ash plumes that rose to altitudes of 2.4-3 km (8,000-10,000 ft) a.s.l. and traveled SE and E. JMA reported that six explosions from Showa Crater during 23-26 August ejected tephra as far as 1,300 m. Incandescence from the crater was visible during 25-26 August.

JMA reported that 24 explosions at Sakura-jima's Showa Crater were detected during 12-19 August and ejected tephra as far as 1.8 km. Incandescence from the crater was observed on 14 August. A very small eruption from Minami-dake Crater occurred on 16 August, producing an ash plume that rose 200 m.

An explosion from Showa Crater on 18 August generated a large ash plume that rose 5 km above the crater and drifted NW. A small pyroclastic flow traveled SE. According to news sources, the 50-minute-long eruption produced ashfall in the central and northern parts of Kagoshima (10 km W), causing train delays and poor visibility for car drivers. The event was the 500th explosion this year.

Based on information from JMA, the Tokyo VAAC reported that during 7-11 and 13 August explosions from Sakura-jima generated plumes that rose to altitudes of 1.8-4.6 km (6,000-15,000 ft) a.s.l. and drifted SE, S, and NW. On 8, 10 and 13 August pilots observed ash plumes that rose to altitudes of 2.7-3 km (9,000-10,000 ft) a.s.l., and traveled SE, S, and vertically, respectively. JMA reported that seven explosions at Showa Crater were detected during 9-12 August and ejected tephra as far as 800 m. A 50-minute-long eruption on 9 August generated an ash plume that rose 3.5 km above the crater.

JMA reported that 10 explosions at Sakura-jima's Showa Crater were detected during 29 July-2 August and ejected tephra as far as 1.3 km. Incandescence from the crater was observed on 1 August. Based on information from JMA, the Tokyo VAAC reported that during 31 July-6 August explosions generated plumes that rose to altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l. and drifted E, SE, and S. On 31 July and 4 August pilots observed ash plumes that rose to altitudes of 2.4-3 km (8,000-10,000 ft) a.s.l. and drifted E.

JMA reported that 10 explosions at Sakura-jima's Showa Crater were detected during 22-26 July, and ejected tephra as far as 1.3 km. Explosions at 1635 and 2333 on 22 July generated ash plumes that rose 3.2 and 3 km above the crater rim, respectively. Based on information from JMA, the Tokyo VAAC reported that during 24-30 July explosions generated plumes that rose to altitudes of 1.8-3.7 km (6,000-12,000 ft) a.s.l. and drifted E and SE. During 24-27 and 29 July pilots observed ash plumes that rose to altitudes of 2.7-5.5 km (9,000-18,000 ft) a.s.l. and drifted E and SE.

JMA reported that five explosions at Sakura-jima's Showa Crater were detected during 16-19 July, and ejected tephra as far as 1.3 km. A large plume rose 3.5 km above the crater on 16 July. Incandescence from the crater was observed at night during 18-19 July. Based on information from JMA, the Tokyo VAAC reported that during 18-21 July explosions generated plumes that rose to altitudes of 2.4-4.3 km (8,000-14,000 ft) a.s.l. and drifted N, E, SE, and S. Ash was sometimes detected in satellite images. On 19 July a pilot observed an ash plume that rose to an altitude of 6.1 km (20,000 ft) a.s.l. and drifted SE.

JMA reported that 17 explosions at Sakura-jima's Showa Crater were detected during 8-15 July; incandescence from the crater was occasionally observed at night. Explosions during 10-11 July generated ash plumes that rose 3-3.4 km above the crater. Based on information from JMA, the Tokyo VAAC reported that during 10-16 July explosions generated plumes that rose to altitudes of 1.5-4.6 km (5,000-15,000 ft) a.s.l. and drifted N, NE, ENE, and E. Ash was detected in satellite images. During 10 and 14-15 July pilots observed ash plumes that rose to altitudes of 1.5-4 km (5,000-13,000 ft) a.s.l. and drifted NE and E.

JMA reported that two explosions at Sakura-jima's Showa Crater were detected during 5-8 July; cloud cover prevented visual observations of the crater. Crater incandescence was occasionally detected at night. Based on information from JMA, the Tokyo VAAC reported that during 8-9 July explosions generated plumes that rose to altitudes of 1.8-3.7 km (6,000-12,000 ft) a.s.l. and drifted NE, E, and SE.

JMA reported that during 25-28 June Sakura-jima's Showa Crater had four explosions, ejecting tephra that fell at most 1.3 km from the crater. Crater incandescence was occasionally detected at night. Based on information from JMA, the Tokyo VAAC reported that on 26 June explosions were detected. Explosions on 1 July generated plumes that rose over 1.2 km (4,000 ft) a.s.l.

JMA reported that during 21-24 June Sakura-jima's Showa Crater had five explosions, ejecting tephra that fell at most 1.3 km from the crater. Crater incandescence was occasionally detected at night. Based on information from JMA, the Tokyo VAAC reported that on 20 June explosions were detected, and on 21 June a pilot observed ash. On 23 and 25 June explosions produced plumes that rose to altitudes of 1.5-1.8 km (5,000-6,000 ft) a.s.l. and drifted E and SE. On 23 June a pilot observed an ash plume that rose to an altitude of 3 km (10,000 ft) a.s.l.

JMA reported that during 10-14 June Sakura-jima's Showa Crater had four explosions, ejecting tephra that fell at most 1.3 km from the crater. Crater incandescence was occasionally detected at night. One of the explosions on 13 June generated an ash plume that rose 3.3 km above the crater rim. Based on information from JMA, the Tokyo VAAC reported that on 16 June plumes rose to an altitude of 2.7 km (9,000 ft) a.s.l.

JMA reported that during 27-31 May Sakura-jima's Showa Crater had four explosions, ejecting tephra that fell at most 1.3 km from the crater. Crater incandescence was occasionally detected at night. A small pyroclastic flow traveled 700 m down the E flank. A pyroclastic flow also occurred in the crater. Based on information from JMA, the Tokyo VAAC reported that on 30 May explosions produced plumes that rose to altitudes of 2.1-2.4 km (7,000-8,000 ft) a.s.l. and drifted E. An explosion was detected on 1 June, and on 2 June an explosion produced an ash plume that rose 1.5 km (5,000 ft) a.s.l.

JMA reported that during 20-24 May Sakura-jima's Showa Crater had eight explosions, ejecting tephra that fell at most 1.3 km from the crater. Crater incandescence was occasionally detected at night. Based on information from JMA, the Tokyo VAAC reported that during 23-26 May explosions produced plumes that rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted E, SW, and W. On 24 May a pilot observed an ash plume that rose to an altitude of 3 km (10,000 ft) a.s.l.

JMA reported that during 13-17 May Sakura-jima's Showa Crater had 13 explosions ejecting tephra that fell at most 1.8 km from the crater. Crater incandescence was occasionally detected at night. Based on information from JMA, the Tokyo VAAC reported that during 15, 17-18, and 20-21 May explosions produced plumes that rose to altitudes of 1.2-3.7 km (4,000-12,000 ft) a.s.l. and drifted E and W. On 21 May a pilot observed an ash plume that rose to an altitude of 3.4 km (11,000 ft) a.s.l. and drifted E.

JMA reported that during 7-10 May eight explosions from Sakura-jima's Showa Crater ejected tephra that fell at most 1.8 km from the crater. Crater incandescence was occasionally detected at night. Based on information from JMA, the Tokyo VAAC reported that on most days during 8-14 May explosions produced plumes that rose to altitudes of 2.1-4.3 km (7,000-14,000 ft) a.s.l. and drifted in multiple directions. During 9 and 13-14 May pilots observed ash plumes rising to altitudes of 2.4-3 km (8,000-10,000 ft) a.s.l. and drifting N, NW, and W.

Based on information from JMA, the Tokyo VAAC reported that during 1-6 April explosions from Sakura-jima generated ash plumes that rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l. and drifted E and SE. A pilot observed an ash plume that rose to an altitude of 2.4 km (8,000 ft) a.s.l. on 3 April. Another ash plume observed by a pilot rose to an altitude of 3.4 km (11,000 ft) a.s.l. and drifted S on 5 May.

JMA reported that during 22-25 April four explosions from Sakura-jima's Showa Crater ejected tephra at most 1.3 km from the crater. Crater incandescence was occasionally detected at night. Based on a pilot report, the Tokyo VAAC reported that ash plumes drifted NE and SE at altitudes of 2.7-3 km (9,000-10,000 ft) a.s.l. during 24-25 April. Explosions on 26 and during 28-29 April produced plumes that rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted SE and NE.

Based on information from JMA, the Tokyo VAAC reported that on 17 April an eruption from Sakura-jima produced an ash plume that rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted E. JMA reported that three large eruptions from Showa Crater occurred during 19-22 April and ejected tephra at most 1.3 km from the crater. Crater incandescence was detected at night.

JMA reported that occasional very small eruptions from Sakura-jima's Showa Crater occurred during 8-12 April. Crater incandescence was detected at night. Based on information from JMA, the Tokyo VAAC reported that on 13 April an eruption produced an ash plume that rose to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted SE.

JMA reported that during 1-5 April three explosions from Sakura-jima's Showa Crater ejected tephra at most 1.8 km from the crater. Crater incandescence was occasionally detected at night. Based on a pilot report, the Tokyo VAAC reported that an ash plume drifted N on 4 April.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 28 March-1 April generated plumes that rose to altitudes of 1.8-2.7 km (6,000-9,000 ft) a.s.l. and drifted NE, E, and SE. JMA reported that during 29 March-1 April four explosions from Showa Crater ejected tephra at most 1.3 km from the crater.

JMA reported that during 18-22 March nine explosions from Sakura-jima's Showa Crater were detected and ejected tephra fell at most 1.3 km from the crater.

Based on information from JMA, the Tokyo VAAC reported that explosions during 20-22 and 25 March generated ash plumes that rose to altitudes of 1.5-2.4 km (5,000-8,000 ft) a.s.l. and drifted NE, E, and SE. A pilot observed an ash plume that drifted E at an altitude of 2.7 km (9,000 ft) a.s.l. on 20 March.

JMA reported that 16 explosions from Sakura-jima's Showa Crater were detected during 11-15 March, ejecting tephra that fell at most 1.8 km from the crater. Crater incandescence was detected at night.

Based on information from JMA, the Tokyo VAAC reported that explosions during 13 and 15-19 March generated ash plumes that rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l. and drifted SE, E, NE, and N. On 15 and 17 March pilots observed ash plumes that rose to altitudes of 1.5-2.4 km (5,000-8,000 ft) a.s.l.

JMA reported that nine explosions from Sakura-jima's Showa Crater were detected during 4-8 March, and ejected tephra fell at most 1.3 km from the crater. Crater incandescence was clearly detected at night.

Based on information from JMA, the Tokyo VAAC reported that explosions during 6-12 March generated plumes that rose to altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l. and drifted SE, E, and NE. Pilots observed ash plumes that rose to altitudes of 1.2-4.6 km (4,000-15,000 ft) a.s.l. during 7-11 March and drifted S and E.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 27 February-3 March and 5 March generated ash plumes that rose to altitudes of 1.8-3.7 km (6,000-12,000 ft) a.s.l. and drifted S, SE, and E. A pilot observed an ash plume that rose to an altitude of 4.3 km (14,000 ft) a.s.l. on 28 February. JMA reported that 10 explosions from Showa Crater were detected during 1-4 March, and ejected tephra fell at most 1.3 km from the crater.

JMA reported that 13 explosions from Sakura-jima's Showa Crater were detected during 18-22 February, and ejected tephra fell at most 1.3 km from the crater. Crater incandescence was clearly detected at night.

Based on information from JMA, explosions from Showa Crater during 20-26 February generated ash plumes that rose to altitudes of 1.2-2.4 km (4,000-8,000 ft) a.s.l. and drifted SE, E, and NE. According to the Tokyo VAAC, a pilot observed an ash plume that drifted ENE at an altitude of 2.1 km (7,000 ft) a.s.l. on 25 February.

JMA reported that during 12-15 February 16 explosions from Sakura-jima's Showa Crater were detected and ejected tephra fell at most 1.3 km from the crater. Crater incandescence was clearly detected at night.

Based on information from JMA, explosions from Sakura-jima's Showa Crater during 13-18 February generated plumes that rose to altitudes of 1.2-3 km (4,000-10,000 ft) a.s.l. and drifted in multiple directions. The Tokyo VAAC reported that pilots observed ash plumes at altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l. during 13 and 15-16 February.

JMA reported that during 28 January-1 February explosions from Sakura-jima's Showa Crater ejected tephra as far as 1.8 km from the crater. Crater incandescence was occasionally detected.

The Tokyo VAAC reported that pilots observed ash plumes at altitudes of 3 km (10,000 ft) a.s.l. during 30-31 January. Based on information from JMA, explosions during 31 January-5 February generated plumes on most days that rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l. and drifted N, NW, and SE.

JMA reported that during 21-25 January explosions from Sakura-jima's Showa Crater ejected tephra as far as 1.3 km from the crater. Crater incandescence was detected on 21 January.

Based on information from JMA, the Tokyo VAAC reported that explosions during 23-29 January generated plumes that rose to altitudes of 1.2-2.4 km (4,000-8,000 ft) a.s.l. and drifted E and SE. Pilots observed ash plumes drifting SE at altitudes of 3 and 2.4 km (10,000 and 8,000 ft) a.s.l. on 27 and 28 January, respectively.

JMA reported that during 15-18 January explosions from Sakura-jima's Showa Crater ejected tephra as far as 1.3 km from the crater. A very small eruption occurred at Minami-dake Crater on 15 January.

Based on information from JMA, the Tokyo VAAC reported that explosions during 16-21 January often generated plumes that rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l. and drifted NE, E, SE, and S. A pilot reported that an ash plume drifted SE at an altitude of 2.4 km (8,000 ft) a.s.l. on 19 January.

JMA reported that during 7-11 January explosions from Sakura-jima's Showa Crater ejected tephra as far as 1.3 km from the crater. Very small eruptions occurred at Minami-dake Crater during 10-11 January.

Based on information from JMA, the Tokyo VAAC reported that explosions during 9-15 January generated plumes that rose to altitudes of 1.2-2.7 km (4,000-9,000 ft) a.s.l. and drifted N, NE, E, SE, and S. Pilots reported that ash plumes drifted E at an altitude of 1.8 km (6,000 ft) a.s.l. on 12 January and drifted SE at altitudes of 2.1-3 km (7,000-10,000 ft) a.s.l. on 15 January.

JMA reported that during 28 December-4 January explosions from Sakura-jima's Showa Crater ejected tephra as far as 1.3 km from the crater. Very small eruptions occurred at Minami-dake Crater on 30 December and 4 January.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 2 and 5-8 January generated plumes that rose to altitudes of 1.2-2.7 km (4,000-9,000 ft) a.s.l. and drifted NE, E, and SE.

JMA reported that during 25-28 December explosions from Sakura-jima's Showa Crater ejected tephra as far as 1.8 km from the crater. A small pyroclastic flow traveled 500 m E. Very small eruptions periodically occurred at Minami-dake Crater.

JMA reported that during 10-14 December explosions from Sakura-jima's Showa Crater ejected tephra as far as 1.8 km from the crater. Very small eruptions occurred at Minami-dake Crater periodically. Based on information from JMA, the Tokyo VAAC reported that explosions during 12-18 December often produced plumes that rose to altitudes of 1.5-2.4 km (5,000-8,000 ft) a.s.l. and drifted N, NE, E, and SE. Pilots reported that ash plumes rose to an altitude of 2.1 km (7,000 ft) a.s.l. on 13 and 16 December.

JMA reported that during 3-7 December explosions from Sakura-jima's Showa Crater ejected tephra as far as 1.3 km from the crater. A very small eruption occurred at Minami-dake Crater on 6 December. Based on information from JMA, the Tokyo VAAC reported that explosions during 5-10 December often produced plumes that rose to altitudes of 1.2-4.3 km (4,000-14,000 ft) a.s.l. and drifted SW, S, SE, and E. A pilot reported that an ash plume drifted E at an altitude of 2.1 km (7,000 ft) a.s.l. on 7 December.

JMA reported that during 26-30 November explosions from Sakura-jima's Showa Crater ejected tephra as far as 1.8 km from the crater. Very small eruptions at Minami-dake Crater occasionally occurred. Based on information from JMA, the Tokyo VAAC reported that explosions during 29 November-4 December produced plumes that rose to altitudes of 1.8-3.7 km (6,000-12,000 ft) a.s.l. and drifted W, E, SE, and S. A pilot reported that an ash plume drifted SE at an altitude of 1.8 km (6,000 ft) a.s.l.

JMA reported that during 19-22 November explosions from Sakura-jima's Showa Crater ejected tephra as far as 1.3 km from the crater. Very small eruptions at Minami-dake Crater occurred during 19-20 November. Based on information from JMA, the Tokyo VAAC reported that explosions during 21-23, 25, and 27 November often produced plumes that rose to altitudes of 1.5-2.7 km (5,000-9,000 ft) a.s.l. and drifted N, NE, E, and SE.

JMA reported that during 12-16 November explosions from Sakura-jima's Showa Crater ejected tephra as far as 1.8 km from the crater. Incandescence from Showa was observed during 12-13 November, and a very small eruption at Minami-dake Crater occurred on 16 November.

Based on information from JMA, the Tokyo VAAC reported that explosions during 14-20 November often produced plumes that rose to altitudes of 1.8-3.4 km (6,000-11,000 ft) a.s.l. and drifted N, NE, E, and SE.

JMA reported that during 5-9 November explosions from Sakura-jima's Showa Crater ejected tephra as far as 1.3 km from the crater. Very small eruptions at Minami-dake Crater occurred during 8-9 November. Based on information from JMA, the Tokyo VAAC reported that explosions during 7-12 November produced plumes that rose to altitudes of 1.2-3 km (4,000-10,000 ft) a.s.l. and drifted S, SE, and E. During 8-9 November pilots observed ash plumes that rose to altitudes of 2.4-4 km (8,000-13,000 ft) a.s.l. and drifted SE and E.

JMA reported that during 29 October-2 November explosions from Sakura-jima's Showa Crater ejected tephra as far as 1.8 km from the crater. A small explosion from Minami-dake Crater occurred during 29-30 October. Based on information from JMA, the Tokyo VAAC reported that explosions during 2-5 and 7 November produced plumes that rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted N, E, and SE. On 5 November a pilot observed an ash plume that rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted E.

JMA reported that explosions from Sakura-jima's Showa Crater during 15-29 October explosions ejected tephra as far as 1.8 km from the crater. A small explosion from Minami-dake Crater occurred on 29 October. Based on information from JMA, the Tokyo VAAC reported that explosions during 24-27 and 29-30 October produced plumes that rose to altitudes of 1.5-3.4 km (4,000-11,000 ft) a.s.l. and drifted N, NE, E, SE, and S. During 24-25 and 29 October pilots observed ash plumes that rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted N and SE.

JMA reported that explosions from Sakura-jima's Showa Crater during 15-19 October explosions ejected tephra as far as 1,300 m from the crater. Based on information from JMA, the Tokyo VAAC reported that explosions during 17-21 October produced plumes that rose to altitudes of 1.8-3.7 km (6,000-12,000 ft) a.s.l. and drifted NE, E, and S. During 21-23 October pilots observed ash plumes that rose to altitudes of 1.8-3.4 km (6,000-11,000 ft) a.s.l. and drifted N and SE.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima's Showa Crater during 12 and 14-15 October produced plumes that rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l. and drifted W, SW, and SE. On 12 October a pilot observed an ash plume that rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted SE. JMA reported that during 12-15 October explosions ejected tephra as far as 800 m from the crater.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima's Showa Crater during 3-9 October produced plumes that rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l. and drifted W, SW, S, SE, and E. JMA reported that during 5-9 October explosions ejected tephra as far as 1.3 km from the crater. An explosion produced a small pyroclastic flow that traveled 300 m down the E side of Showa Crater.

JMA reported that during 24-28 September explosions from Sakura-jima's Showa Crater ejected tephra as far as 1.8 km from the crater. Based on information from JMA, the Tokyo VAAC reported that explosions during 26 September-2 October often produced plumes that rose to altitudes of 1.8-3.4 km (6,000-11,000 ft) a.s.l. and drifted W, S, SE, and E. During 26-27 September pilots observed ash plumes that rose to altitudes of 1.2-3.4 km (4,000-11,000 ft) a.s.l. and drifted SE.

JMA reported that during 15-21 September explosions from Sakura-jima's Showa Crater ejected tephra as far as 1.3 km from the crater. Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 19-20 and 22-24 September often produced plumes that rose to altitudes of 1.8-3.4 km (6,000-11,000 ft) a.s.l. The plumes sometimes drifted NE, E, SE, S, and SW. On 19 September a pilot observed an ash plume that rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted SE.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 13-15 and 17-18 September often produced plumes that rose to altitudes of 2.1-3.7 km (7,000-12,000 ft) a.s.l. The plumes sometimes drifted NW, N, and NE. On 14 September a pilot observed an ash plume that rose to an altitude of 3.4 km (11,000 ft) a.s.l.

JMA reported that during 3-7 September six explosive eruptions from Sakura-jima's Showa Crater ejected tephra as far as 1.3 km from the crater. Incandescence from the crater was observed at night. Based on information from JMA, the Tokyo VAAC reported that explosions during 6-11 September often produced plumes that rose to altitudes of 1.8-4.6 km (6,000-15,000 ft) a.s.l. The plumes sometimes drifted N, NE, and SE. On 10 September a pilot observed an ash plume that rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted E.

JMA reported that during 27-31 August five explosive eruptions from Sakura-jima's Showa Crater were detected and ejected tephra as far as 1.3 km from the crater. Gas measurements taken on 20 and 22 August showed elevated sulfur dioxide emissions compared to the previous week. Based on information from JMA, the Tokyo VAAC reported that explosions during 29-30 August and 1-4 September often produced plumes that rose to altitudes of 1.8-3.7 km (6,000-12,000 ft) a.s.l. The plumes sometimes drifted N and NE. Pilots observed ash plumes during 1-2 September that rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l.

JMA reported that during 20-24 August eight explosive eruptions from Sakura-jima's Showa Crater were detected and ejected tephra as far as 1.8 km from the crater. Gas measurements taken on 20 and 22 August showed elevated sulfur dioxide emissions compared to the previous week. Based on information from JMA, the Tokyo VAAC reported that explosions during 22-26 August produced plumes that rose to altitudes of 1.8-2.7 km (6,000-9,000 ft) a.s.l. and drifted N, NW, and W. Explosions were detected on 28 August.

JMA reported that during 17-20 August explosions from Sakura-jima's Showa Crater ejected tephra as far as 1,300 m from the crater. Based on information from JMA, the Tokyo VAAC reported that explosions during 17-21 August produced plumes that rose to altitudes of 2.4-3.4 km (8,000-11,000 ft) a.s.l. and drifted N and NW. Pilots observed ash plumes during 18-20 August that rose to altitudes of 2.1-4.3 km (7,000-14,000 ft) a.s.l. and drifted S, SW, and W.

According to a news report, the total amount of ash emitted from Sakura-jima from January to July was more than two times larger than all of 2011, when a record number of eruptions had occurred.

JMA reported that during 6-10 August nine explosions from Sakura-jima's Showa Crater ejected tephra as far as 1,300 m from the crater. Based on information from JMA, the Tokyo VAAC reported that explosions during 8-14 August often produced plumes that rose to altitudes of 1.8-3.7 km (6,000-12,000 ft) a.s.l. and drifted N and NE. A pilot observed an ash plume on 8 August.

JMA reported that during 30 July-3 August three explosions from Sakura-jima's Showa Crater ejected tephra as far as 800 m from the crater. A small explosion from Minami-dake Crater occurred on 31 July. Based on information from JMA, the Tokyo VAAC reported that explosions during 1 and 3-7 July often produced plumes that rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted SW, W, and NW.

JMA reported that during 24-27 July twenty explosions from Sakura-jima's Showa Crater ejected tephra as far as 1,300 m from the crater. An explosion on 26 July produced a large ash plume. Based on information from JMA, the Tokyo VAAC reported that explosions during 25-26 and 28-31 July produced plumes that rose to altitudes of 1.5-3.7 km (5,000-12,000 ft) a.s.l. and drifted SW, W, NW, and N. Pilots observed ash plumes during 25-26 and 29 July that rose to altitudes of 2.4-3.4 km (8,000-11,000 ft) a.s.l.

JMA reported that during 20-23 July eight explosions from Sakura-jima's Showa Crater ejected tephra as far as 1,300 m from the crater. Incandescence from the crater was visible at night during 22-23 July. Based on information from JMA, the Tokyo VAAC reported that explosions during 18-24 July produced plumes that rose to altitudes of 1.8-3.4 km (6,000-11,000 ft) a.s.l. and drifted in multiple directions. Pilots observed ash plumes on 22 and 24 July that rose to altitudes of 2.4-6.1 km (8,000-20,000 ft) a.s.l. JMA reported that an explosion on 24 July from Minami-dake Crater ejected tephra as far as 1,700 m from the crater.

JMA reported that explosions from Sakura-jima's Showa Crater on 13, 15, and 17 July ejected tephra as far as 1,300 m from the crater. Based on information from JMA, the Tokyo VAAC reported that an explosion on 10 July produced an ash plume that rose to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted N. Explosions during 16-17 July produced plumes that rose to an altitude of 1.8-3 km (6,000-10,000 ft) a.s.l. and drifted NE, N, NW, and W.

JMA reported that during 2-6 July explosions from Sakura-jima's Showa Crater ejected tephra as far as 1,300 m from the crater. Based on information from JMA, the Tokyo VAAC reported multiple explosions during 4-10 July; plumes rose to altitudes of 1.8-3.7 km (6,000-12,000 ft) a.s.l. and drifted E, SE, and N. A pilot observed an ash plume on 4 July that rose to an altitude of 2.4 (8,000 ft) a.s.l.

JMA reported that during 25-29 June large explosive eruptions from Sakura-jima's Showa Crater occurred ten times and ejected tephra as far as 1,300 m from the crater.

Based on information from JMA, the Tokyo VAAC reported multiple explosions during 27 June-1 July. The explosions sometimes produced plumes that rose to altitudes of 1.5-2.1 km (5,000-7,000 ft) a.s.l. and drifted E, NE, and NW. A pilot observed an ash plume on 28 June that rose to an altitude of 1.8 (6,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that on 20 and 22 June explosions from Sakura-jima produced plumes that rose to altitudes of 2.4-3.7 km (8,000-12,000 ft) a.s.l. and drifted E. A pilot observed an ash plume on 20 June that rose to an altitude of 3.7 (12,000 ft) a.s.l. and drifted E. JMA reported that during 22-25 June large explosive eruptions from Showa Crater occurred five times and ejected tephra as far as 1,300 m from the crater. According to VAAC reports on 26 June, explosions were detected and an ash plume rose to altitudes of 1.5-1.8 km (5,000-6,000 ft) a.s.l. and drifted W.

JMA reported that during 11-15 June large explosive eruptions from Sakura-jima's Showa Crater occurred five times and ejected tephra as far as 800 m from the crater. A small eruption from Minami-dake Crater occurred on 13 June.

Based on information from JMA, the Tokyo VAAC reported that during 13-15 and 17-19 June explosions produced plumes that rose to altitudes of 1.8-3.4 km (6,000-11,000 ft) a.s.l. and drifted multiple directions. A pilot observed an ash plume on 19 June that rose to an altitude of 3.4 (11,000 ft) a.s.l. and drifted E.

JMA reported that during 4-8 June explosive eruptions from Sakura-jima's Showa Crater occurred 11 times and ejected tephra as far as 1.3 km from the crater. A small pyroclastic flow traveled 200 m down the E flank.

Based on information from JMA, the Tokyo VAAC reported that during 6-7 and 9-11 June explosions produced plumes that rose to altitudes of 1.2-3.7 km (4,000-12,000 ft) a.s.l. and drifted multiple directions. Pilots observed ash plumes during 6-7 June that rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l. and drifted S, E, and NE. Explosions were detected on 8 and 12 June.

JMA reported that during 1-4 June seven explosions from Sakura-jima's Showa Crater ejected ballistics 800-1,300 m from the crater. Based on information from JMA, the Tokyo VAAC reported that during 30 May-5 June explosions produced plumes that rose to altitudes of 1.2-3 km (4,000-10,000 ft) a.s.l. and drifted SW, W, and NW. Pilots observed ash plumes during 3-4 June that rose to altitudes of 2.7-3.4 (9,000-11,000 ft) a.s.l. and drifted W.

JMA reported eight explosive eruptions from Sakura-jima's Showa Crater during 21-25 May and a small eruption from Minami-dake Crater on 23 May. Based on information from JMA, the Tokyo VAAC reported that during 23-24 and 26-28 May explosions produced plumes that rose to altitudes of 1.8-4.6 km (6,000-15,000 ft) a.s.l. and drifted SW, S, SE, E, and NE.

Based on information from JMA, the Tokyo VAAC reported that during 16-20 and 22 May explosions from Sakura-jima produced plumes that rose to altitudes of 1.8-3.7 km (6,000-12,000 ft) a.s.l. and drifted multiple directions. Pilots observed ash plumes during 16-17 May that rose to altitudes of 2.7-4 km (9,000-13,000 ft) a.s.l. and drifted E and SE. Explosions were detected during 21-22 May.

JMA reported that during 18-21 May explosive eruptions from Showa Crater occurred multiple times and ejected tephra as far as 1.8 km from the crater. Incandescence from the crater was observed at night. Very small eruptions from Minami-dake Crater occurred on 18 and 19 May, and a small pyroclastic flow traveled 300 m down the Showa crater flanks on 21 May.

JMA reported that during 11-15 May explosive eruptions from Sakura-jima's Showa Crater occurred nine times and ejected tephra as far as 1.3 km from the crater. Based on information from JMA, the Tokyo VAAC reported that during 9 and 11-15 May explosions produced plumes that rose to altitudes of 1.8-2.7 km (6,000-9,000 ft) a.s.l. and drifted SW, S, SE, E, and N. A pilot observed an ash plume on 12 May that rose to an altitude of 2.1 (7,000 ft) a.s.l. and drifted E.

JMA reported that during 1-7 May explosive eruptions from Sakura-jima's Showa Crater occurred 17 times and ejected tephra as far as 1.3 km from the crater. Very small eruptions from Minami-dake Crater occurred on 3 and 5 May. Based on information from JMA, the Tokyo VAAC reported that during 3-4 and 6-8 May explosions produced plumes that rose to altitudes of 1.5-3.7 km (5,000-12,000 ft) a.s.l. and drifted S, SE, and E. Ash was observed in satellite imagery on 3 May. A pilot observed an ash plume on 7 May that rose to an altitude of 2.4 (8,000 ft) a.s.l. and drifted SE.

Based on information from JMA, the Tokyo VAAC reported that during 24 April-1 May explosions from Sakura-jima produced plumes that rose to altitudes of 1.8-2.7 km (6,000-9,000 ft) a.s.l. and drifted in multiple directions. A pilot observed an ash plume on 26 April that rose to an altitude of 2.7 (9,000 ft) a.s.l.

On 6, 8, and 10 April a visitor to Sakura-jima observed and photographed several Vulcanian explosions from Showa crater and noted that the crater was approximately 20% wider from N to S that in the beginning of 2010.

Based on information from JMA, the Tokyo VAAC reported that during 21-22 March explosions from Sakura-jima produced ash plumes that rose to altitudes of 1.8-2.7 km (6,000-9,000 ft) a.s.l. and drifted NE and S.

JMA reported that on 12 March an explosion from Sakura-jima's Showa crater ejected tephra that landed as far as 2 km from the crater. Based on information from JMA, the Tokyo VAAC reported that during 14-21 March explosions often produced plumes that rose to altitudes of 1.5-2.7 km (5,000-9,000 ft) a.s.l. and drifted N, NW, and SE. Pilots observed ash plumes during 18-20 March that rose to altitudes of 1.2-4 km (4,000-13,000 ft) a.s.l. and drifted SE and E.

Based on information from JMA, the Tokyo VAAC reported that during 7-9 and 11-13 March explosions from Sakura-jima often produced plumes that rose to altitudes of 1.2-2.7 km (4,000-9,000 ft) a.s.l. and drifted E and SE. Pilots observed ash plumes during 9 and 11-13 March that rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that during 29 February-7 March explosions from Sakura-jima often produced plumes that rose to altitudes of 1.2-3 km (4,000-10,000 ft) a.s.l. and drifted NW, E, and SE. A pilot observed an ash plume on 5 March. Another pilot report on 6 March noted a plume drifting SE at an altitude of 2.4 km (8,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that on 22 and 24 February explosions from Sakura-jima produced plumes that rose to altitudes of 1.5-1.8 km (5,000-6,000 ft) a.s.l. and drifted NE.

Based on information from JMA, the Tokyo VAAC reported that during 15-16 and 18-21 February explosions from Sakura-jima produced plumes that rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted NE, E, and SE.

Based on information from JMA, the Tokyo VAAC reported that during 8-14 February explosions from Sakura-jima produced plumes that rose to altitudes of 1-3 km (3,000-10,000 ft) a.s.l. and drifted E and SE. On 11 February an ash plume that rose to an altitude of 2.4 km (8,000 ft) a.s.l., drifted E, and later dissipated. A pilot observation indicated an ash plume rising to an altitude of 1.8 km (6,000 ft) a.s.l. and drifting NE on 11 February.

Based on information from JMA, the Tokyo VAAC reported that during 1-7 February explosions from Sakura-jima produced plumes that rose to altitudes of 1.2-3.7 km (4,000-12,000 ft) a.s.l. and drifted E and SE. On 5 and 6 February pilots observed ash plumes that rose to an altitude of 2.1 km (7,000 ft) a.s.l. and 3.7 km (12,000 ft) a.s.l. respectively.

Based on information from JMA, the Tokyo VAAC reported that during 25-27 and 29-30 January explosions from Sakura-jima produced plumes that rose to altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l. and drifted E and SE. On 29 January a pilot observed an ash plume that rose to an altitude of 2.1 km (7,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that during 18-24 January explosions from Sakura-jima produced plumes that rose to altitudes of 1.5-2.7 km (5,000-9,000 ft) a.s.l. and drifted N, NE, E, and SE. On 20 January a pilot observed an ash plume that rose to an altitude of 1.8 km (6,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that during 11-17 January explosions from Sakura-jima produced plumes that rose to altitudes of 1.2-2.4 km (4,000-8,000 ft) a.s.l. and drifted NE, E, and SE. On 14 January a pilot observed an ash plume that rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted S.

Based on information from JMA, the Tokyo VAAC reported that during 4-10 January explosions from Sakura-jima produced plumes that rose to altitudes of 1.5-2.7 km (5,000-9,000 ft) a.s.l. and drifted NE, E, SE, and S. On 7 January an ash plume rose to an altitude 2.7 km (9,000 ft) a.s.l. and drifted SE, then later dissipated.

Based on information from JMA, the Tokyo VAAC reported that during 28 and 30 December-3 January explosions from Sakura-jima produced plumes that rose to altitudes of 1.5-2.7 km (5,000-9,000 ft) a.s.l. and drifted NE, E, SE, and S.

Based on information from JMA, the Tokyo VAAC reported that during 21-27 December explosions from Sakura-jima produced plumes that rose to altitudes of 1.5-2.7 km (5,000-9,000 ft) a.s.l. and drifted E, SE, S, and NE. Satellite imagery on 23 December showed ash emissions that later dissipated. On 27 December observations from satellite images and a pilot report showed an ash plume that rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted 9 km E.

Based on information from JMA, the Tokyo VAAC reported that during 14-20 December explosions from Sakura-jima produced plumes that rose to altitudes of 1.2-2.4 km (4,000-8,000 ft) a.s.l. and drifted SE and S. On 15 December satellite imagery showed ash emissions that later dissipated. A pilot reported that an ash plume rose to an altitude of 1.5 km (5,000 ft) and drifted 32 km S on 18 December.

Based on information from JMA, the Tokyo VAAC reported that during 7-13 December explosions from Sakura-jima produced plumes that rose to altitudes of 1.0-2.7 km (3,000-9,000 ft) a.s.l. and drifted E, SE, S, and NE. Satellite imagery and a pilot report showed ash plumes that rose to an altitude of 2.4 km (8,000 ft) a.s.l and drifted 46 km SW on 9 December and 37 km S on 13 December.

Based on information from JMA, the Tokyo VAAC reported that during 30 November and 2-6 December explosions from Sakura-jima produced plumes that rose to altitudes of 1.2-3.0 km (4,000-10,000 ft) a.s.l. and drifted NE, E, SE, W, NW. Satellite imagery and a pilot report on 30 November showed an ash plume at an altitude 3.7 km (12,000 ft) a.s.l and drifted 37 km SE. On 5 December a pilot report and satellite imagery showed an ash plume at an altitude of 3.7 km (12,000 ft) a.s.l and drifted 74 km S.

Based on information from JMA, the Tokyo VAAC reported that during 23 and 25-29 November explosions from Sakura-jima produced plumes that rose to altitudes of 1.8-2.7 km (6,000-9,000 ft) a.s.l. and drifted W, S, E, and NE.

Based on information from JMA, the Tokyo VAAC reported that during 16-17 and 19-22 November explosions from Sakura-jima produced plumes that rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l. and drifted S, SE, E, and N. Satellite imagery on 16 and 21 November showed ash emissions that later dissipated. On 19 November a pilot reported an ash plume at an altitude of 3 km (10,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that during 9-12 and 14-15 November explosions from Sakura-jima produced plumes that rose to altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l. and drifted W, S, and SE. On 14 November a pilot reported that an ash plume rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted SE. Satellite imagery during 14-15 November showed ash emissions that later dissipated.

Based on information from JMA, the Tokyo VAAC reported that during 2-3 and 5-7 November explosions from Sakura-jima produced plumes that rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l. and drifted W, NW, N, and SE.

Based on information from JMA, the Tokyo VAAC reported that during 26 October-1 November explosions from Sakura-jima produced plumes that rose to altitudes of 1.8-3.4 km (6,000-11,000 ft) a.s.l. and drifted NW, W, SW, S, and SE. Satellite imagery on 26 October detected ash plumes that later dissipated. A pilot observed an ash plume on 31 October that rose to an altitude of 2.7 km (9,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that during 20-25 October explosions from Sakura-jima produced plumes that rose to altitudes of 1.8-3.4 km (6,000-11,000 ft) a.s.l. and drifted W, NW, E, and SE. Pilots observed ash plumes that rose to altitudes of 3 and 1.5 km (10,000 and 5,000 ft) a.s.l. on 23 and 25 October, respectively. The plumes drifted SE on both days.

Based on information from JMA, the Tokyo VAAC reported that during 12-13 and 15-18 October explosions from Sakura-jima produced plumes that rose to altitudes of 1.8-3.4 km (6,000-11,000 ft) a.s.l. and drifted SE and E. On 18 October a pilot observed an ash plume that rose to an altitude of 3 km (10,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that during 5-11 October explosions from Sakura-jima produced plumes that rose to altitudes of 1.2-3 km (4,000-10,000 ft) a.s.l. and drifted NW, N, SE, and S. During 6-8 October pilots observed ash plumes that rose to altitudes of 1.8-3.7 km (6,000-12,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that during 28 September-3 October explosions from Sakura-jima produced plumes that rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l. and drifted in multiple directions. On 30 September and during 1-2 October pilots observed ash plumes that rose to altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l. and mostly drifted NE, E, and ESE.

Based on information from JMA, the Tokyo VAAC reported that during 21-27 September explosions from Sakura-jima produced plumes that rose to altitudes of 1.5-2.7 km (5,000-9,000 ft) a.s.l. and drifted SE, S, and W. On 22 September a pilot observed an ash plume that rose to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted SE.

Based on information from JMA, the Tokyo VAAC reported that during 14-20 September explosions from Sakura-jima produced plumes that rose to altitudes of 1.2-3 km (4,000-10,000 ft) a.s.l. and drifted S, SW, W, and NW. On 14 September a pilot observed an ash plume that rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted W.

Based on information from JMA, the Tokyo VAAC reported that during 9-13 September explosions from Sakura-jima produced plumes that rose to altitudes of 1.8-2.7 km (6,000-9,000 ft) a.s.l. and drifted NW and N. On 9 September a pilot observed an ash plume that rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted NW.

Based on information from JMA, the Tokyo VAAC reported that during 31 August-6 September explosions from Sakura-jima produced plumes that rose to altitudes of 1.2-3 km (4,000-10,000 ft) a.s.l. and drifted SW, S, and SE. According to a news article, the 660th explosive eruption in 2010 occurred on 3 September. The article also noted that as of 2 September, 607 grams of ash per square meter had fallen in Kagoshima (10 km W), compared to 753 grams for all of 2010, when the volcano had a record-high 896 explosive eruptions.

Based on information from JMA, the Tokyo VAAC reported that during 23-30 August explosions from Sakura-jima produced plumes that rose to altitudes of 1.2-3 km (4,000-10,000 ft) a.s.l. and drifted SW, W, NW, N, and NE. On 30 August a pilot observed an ash plume that rose to an altitude of 1.2 km (4,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that during 17-22 August explosions from Sakura-jima often produced plumes that rose to altitudes of 1.2-2.4 km (4,000-8,000 ft) a.s.l. and drifted E. On 18 August, a pilot observed an ash plume that rose to an altitude of 1.8 km (6,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that during 10-16 August explosions from Sakura-jima produced plumes that rose to altitudes of 1.5-3.7 km (5,000-12,000 ft) a.s.l. On 12 August, a pilot observed an ash plume that rose to an altitude of 2.4 km (8,000 ft) a.s.l.

The Tokyo VAAC reported that on 3 August an ash plume from Sakura-jima observed by a pilot rose to an altitude of 1.5 km (5,000 ft) a.s.l. Based on information from JMA, plumes rose to altitudes of 1.5-2.4 km (5,000-8,000 ft) a.s.l. and drifted W, NW, and NE during 3 and 5-9 August.

Based on information from JMA, the Tokyo VAAC reported that during 13-19 July plumes from Sakura-jima rose to altitudes of 1.2-2.7 km (4,000-9,000 ft) a.s.l. Plumes occasionally drifted W, NW, and N. On 18 July, a pilot observed an ash plume that rose to an altitude of 2.1 km (7,000 ft) a.s.l. Explosions were reported the next day.

According to pilot observations, the Tokyo VAAC reported that on 7 and 10 July ash plumes rose from Sakura-jima to altitudes of 1.2-2.4 km (4,000-8,000 ft) a.s.l. Reports from JMA stated that plumes rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. on 8, 10, and 12 July.

According to pilot observations, the Tokyo VAAC reported that ash plumes rose from Sakura-jima to altitudes of 2.1-2.4 km (7,000-8,000 ft) a.s.l on 28 and 30 July. Reports from JMA stated that plumes rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. during 30 June-1 July. An explosion was noted on 4 July.

Based on information from JMA, the Tokyo VAAC reported that on 22, 25, and 28 June plumes from Sakura-jima rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted N and NE. During 27-28 June, pilots observed ash plumes that rose to altitudes of 2.1-3 km (7,000-10,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that during 8-9 and 14 June explosions from Sakura-jima produced plumes that rose to altitudes of 2.1-3 km (7,000-10,000 ft) a.s.l. and drifted E and SE. During 8-9 and 13-14 June, pilots observed ash plumes that rose to altitudes of 2.4-3.7 km (8,000-12,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that during 2-6 June explosions from Sakura-jima produced plumes that rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l. Plumes drifted S on 2 June. On 2 and 4 June, pilots observed ash plumes that rose to altitudes of 2.4-3.7 km (8,000-12,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that during 25-30 May explosions from Sakura-jima frequently produced plumes that rose to altitudes of 1.2-2.4 km (4,000-8,000 ft) a.s.l. Plumes drifted N, NW, E, SE, and S. On 27 May, a pilot observed an ash plume that rose to an altitude of 2.7 km (9,000 ft) a.s.l. and drifted E.

Based on information from JMA, the Tokyo VAAC reported that during 18-22 May explosions from Sakura-jima produced plumes that rose to altitudes of 1.2-3 km (4,000-10,000 ft) a.s.l. Plumes drifted in multiple directions. On 21 May, a pilot observed an ash plume that rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted N.

Based on information from JMA, the Tokyo VAAC reported that during 11-18 May explosions from Sakura-jima sometimes produced plumes that rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. Plumes occasionally drifted SE and S. During 11, 13-14, and 17 May, pilots observed ash plumes that rose to altitudes of 2.1-3 km (7,000-10,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that during 6-10 May explosions from Sakura-jima produced plumes that rose to altitudes of 1.2-2.4 km (4,000-8,000 ft) a.s.l. Plumes sometimes drifted NW, NE, E, SE, and S. On 4 and 9 May, pilots observed ash plumes that rose to altitudes of 2.1-2.7 km (7,000-9,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that during 27-30 April and 2-3 May explosions from Sakura-jima produced plumes that rose to altitudes of 1.8-2.7 km (6,000-9,000 ft) a.s.l. and drifted N, NE, E, SE, and S. On 29 April and 2 May, pilots observed ash plumes that rose to altitudes of 1.8-2.7 km (6,000-9,000 ft) a.s.l. and drifted S and SE.

Based on information from JMA, the Tokyo VAAC reported that during 21-25 April explosions from Sakura-jima produced plumes that rose to altitudes of 1.2-3 km (4,000-10,000 ft) a.s.l. and occasionally drifted N, NE, E, and SE. On 21 and 25 April, pilots observed ash plumes that rose to altitudes of 2.7-3.4 km (9,000-11,000 ft) a.s.l.

Based on information from JMA and pilot observations, the Tokyo VAAC reported that during 13-19 April explosions from Sakura-jima mostly generated ash plumes that rose to altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l. and drifted S, SE, and E.

On 6, 9, and 12 April, pilots observed ash plumes from Sakura-jima that rose to altitudes of 2.7-3 km (9,000-10,000 ft) a.s.l. Plumes on 9 April drifted SE and plumes on 12 April drifted S. Based on information from JMA, the Tokyo VAAC reported that during 7-12 April explosions produced plumes that rose to altitudes of 1.2-2.4 km (4,000-8,000 ft) a.s.l. and occasionally drifted NE, E, SE, and S.

Based on information from JMA, the Tokyo VAAC reported that during 1 and 3-5 April explosions from Sakura-jima produced plumes that rose to altitudes of 1.5-4 km (5,000-13,000 ft) a.s.l. and occasionally drifted E. A video of activity from 4 April showed incandescence emanating from the crater and a few explosions that ejected incandescent material onto the flanks. On 5 April, a pilot observed an ash plume that rose to an altitude of 2.7 km (9,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that during 23-26 and 29 March explosions from Sakura-jima produced plumes that rose to altitudes of 1.2-2.4 km (4,000-8,000 ft) a.s.l. and occasionally drifted E, SE, and S. On 26 March, a pilot observed an ash plume that rose to an altitude of 3.4 km (11,000 ft) a.s.l. and drifted SE.

Based on information from JMA and pilot observations, the Tokyo VAAC reported that during 16-19 and 21-22 March explosions from Sakura-jima produced ash plumes that rose to altitudes of 1.2-3 km (4,000-10,000 ft) a.s.l. and drifted NE, E, and SE. Explosions were reported on 20 March.

Based on information from JMA, the Tokyo VAAC reported that during 9-15 March explosions from Sakura-jima produced plumes that rose to altitudes of 1.2-2.1 km (4,000-7,000 ft) a.s.l. and drifted NW, N, NE, E, and SE. On 12 March, a pilot reported that an ash plume rose to an altitude of 2.7 km (9,000 ft) a.s.l. Another ash plume also observed by a pilot rose to an altitude of 1.5 km (5,000 ft) a.s.l. on 15 March.

Based on information from JMA, the Tokyo VAAC reported that during 2-5 and 8 March explosions from Sakura-jima produced plumes that rose to altitudes of 1.2-1.8 km (4,000-6,000 ft) a.s.l. and drifted E, SE, and S. During 2-4 and 5 March, pilots reported that ash plumes rose to altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l. Some plumes drifted N and SE.

Based on information from JMA, the Tokyo VAAC reported that during 23 February-2 March explosions from Sakura-jima sometimes produced plumes that rose to altitudes of 1.5-2.7 km (5,000-9,000 ft) a.s.l. and drifted in multiple directions. On 23 and 26 February, pilots reported that ash plumes rose to altitudes of 3 and 4 km (10,000 and 13,000 ft) a.s.l. and drifted E and NW, respectively.

Based on information from JMA, the Tokyo VAAC reported that during 16-17 and 19-22 February explosions from Sakura-jima sometimes produced plumes that rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. Some plumes drifted W, SW, and ESE. During 21-22 February, pilots reported that ash plumes rose to altitudes of 2.4-2.7 km (8,000-9,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that during 9 and 11-15 February explosions from Sakura-jima sometimes produced plumes that rose to altitudes of 1.5-2.1 km (5,000-7,000 ft) a.s.l. and drifted S, SE, and E. On 10, 13, and 15 February, pilots reported that ash plumes rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that during 1-8 February explosions from Sakura-jima produced plumes that rose to altitudes of 1.2-3.4 km (4,000-11,000 ft) a.s.l. and drifted SE, E, and NE. During 3-4 and 7 February, pilots reported that ash plumes rose to altitudes of 2.4-3 km (8,000-10,000 ft) a.s.l. According to a news article, an eruption on 8 February produced a gas-and-ash plume that rose 2 km. A large amount of ashfall prompted local authorities to temporarily ban residents from driving near the area.

Based on information from JMA, the Tokyo VAAC reported that during 26 January-1 February explosions from Sakura-jima produced plumes that rose to altitudes of 1.2-2.4 km (4,000-8,000 ft) a.s.l. and drifted SE and E. On 31 January, a pilot reported that an ash plume rose to an altitude of 2.7 km (9,000 ft) a.s.l. and drifted SE.

Based on information from JMA, the Tokyo VAAC reported that during 19 and 21-23 January explosions from Sakura-jima produced plumes that rose to altitudes of 1.5-2.4 km (5,000-8,000 ft) a.s.l. and drifted SE and E. On 22 January, a pilot reported that an ash plume rose to an altitude of 2.7 km (9,000 ft) a.s.l. and drifted E.

Based on information from JMA, the Tokyo VAAC reported that during 13 and 16-18 January explosions from Sakura-jima produced plumes that rose to altitudes of 1.5-2.4 km (5,000-8,000 ft) a.s.l. and drifted SE. On 17 January, a pilot reported that an ash plume rose to altitudes of 1.2-2.1 km (4,000-7,000 ft) a.s.l. and drifted SE.

Based on information from JMA, the Tokyo VAAC reported that during 7-8 January explosions from Sakura-jima produced plumes that rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted E and SE. On 8 January, pilots reported that ash plumes rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l. and drifted SE.

Based on information from JMA, the Tokyo VAAC reported that on 2 January a plume from Sakura-jima rose to an altitude of 1.8 km (6,000 ft) a.s.l. An explosion was noted the next day. An explosion on 5 January produced a plume that rose to an altitude of 1.2 km (4,000 ft) a.s.l. and drifted E.

Based on pilot observations, the Tokyo VAAC reported that on 18 December ash plumes from Sakura-jima rose to altitudes of 2.4-4.9 km (8,000-16,000 ft) a.s.l. and drifted SE. The next day satellite imagery showed that the ash had dissipated.

Based on information from JMA and analysis of satellite imagery, the Tokyo VAAC reported that on 8 December an eruption from Sakura-jima produced an ash plume that rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted E and SE. During 11-12 December explosions produced plumes that rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted SE and E. On 12 December a pilot observed an ash plume that rose to an altitude of 2.7 km (9,000 ft) a.s.l. and drifted NE and E.

Based on information from JMA, the Tokyo VAAC reported that during 1-7 December explosions from Sakura-jima produced plumes that rose to altitudes of 1.2-2.7 km (4,000-9,000 ft) a.s.l. and drifted E, SE, W, NW, and N. During 2 and 4-5 December, pilots reported that ash plumes rose to altitudes of 1.5-4.6 km (5,000-15,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that during 24 November-1 December explosions from Sakura-jima produced plumes that rose to altitudes of 1.2-1.8 km (4,000-6,000 ft) a.s.l. and drifted E, SE, and S. During 24 and 28-29 November, pilots reported that ash plumes rose to altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l. and drifted SE and E.

Based on information from JMA and pilot observations, the Tokyo VAAC reported that during 17, 19-21, and 23 November ash plumes from Sakura-jima rose to altitudes of 1.2-3 km (4,000-10,000 ft) a.s.l. and drifted E, NE, and SE.

Based on information from JMA, the Tokyo VAAC reported that during 10-16 November explosions from Sakura-jima produced plumes that rose to altitudes of 1.2-2.4 km (4,000-8,000 ft) a.s.l. and drifted E, SE, and S. During 15-16 November, pilots reported that ash plumes rose to altitudes of 1.5-2.7 km (5,000-9,000 ft) a.s.l.

Based on information from JMA and pilot observations, the Tokyo VAAC reported that during 3-5 and 7-9 November explosions from Sakura-jima produced ash plumes that rose to altitudes of 1.5-4.3 km (5,000-14,000 ft) a.s.l. and drifted E, ESE, and SE.

Based on information from JMA, the Tokyo VAAC reported that an eruption from Sakura-jima on 31 October produced a plume that rose to an altitude of 1.5 km (6,000 ft) a.s.l. and drifted NE. On 2 November a pilot reported that an ash plume rose to an altitude of 1.5 km (6,000 ft) a.s.l. and drifted SE.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 13-16 October produced plumes that rose to altitudes of 1.5-2.1 km (6,000-7,000 ft) a.s.l. and drifted NE, E, SE, and S. During 15-16 October pilots reported that ash plumes rose to altitudes of 1.5-1.8 km (5,000-6,000 ft) a.s.l. and drifted E and S.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 7-10 October produced plumes that rose to altitudes of 1.5-2.1 km (6,000-7,000 ft) a.s.l. and drifted NW, NE, SE, and S. On 8 October a pilot reported that an ash plume rose to an altitude of 2.7 km (9,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported an eruption from Sakura-jima on 15 September. That same day a pilot observed an ash plume at an altitude of 3 km (10,000 ft) a.s.l. On 16 September a pilot reported that an ash plume rose to an altitude of 1.8 km (6,000 ft) and drifted SE.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima on 8 and 10 September produced plumes that rose to altitudes of 1.5-1.8 km (6,000-8,000 ft) a.s.l. Some of the plumes drifted E and NE. On 9 September a pilot reported that an ash plume rose to an altitude of 3 km (10,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 1-5 September produced plumes that rose to altitudes of 1.5-2.4 km (5,000-8,000 ft) a.s.l. Some of the plumes drifted N, NW, and W. During 2-4 September pilots reported that ash plumes rose to altitudes of 2.1-3.4 km (7,000-11,000 ft) a.s.l. An explosion also occurred on 7 September.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 26-31 August produced plumes that rose to altitudes of 1.2-2.1 km (4,000-7,000 ft) a.s.l. Some of the plumes drifted N and NW.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima on 18, 21, and 23 August produced plumes that rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted W and NW. On 19 and 24 August pilots observed ash plumes that rose to altitudes of 1.5-2.7 km (5,000-9,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 4-9 August produced plumes that rose to altitudes of 1.2-2.4 km (4,000-8,000 ft) a.s.l. and drifted W, NW, and N. Pilots observed ash plumes that rose to altitudes of 2.1-3 km (7,000-10,000 ft) a.s.l. on 7, 9, and 10 August.

Based on information from JMA, the Tokyo VAAC reported an explosion on 29 July. Explosions during 31 July-1 August and 3 August produced plumes that rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted E and SW. On 2 July a pilot observed an ash plume that rose to an altitude of 3 km (10,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that during 21-27 July explosions from Sakura-jima produced plumes. Those plumes, along with ash plumes occasionally seen by pilots, rose to altitudes of 1.2-4.6 km (4,000-15,000 ft) a.s.l. Most plumes rose vertically while others drifted N and NW.

Based on JMA notices, the Tokyo VAAC reported explosions from Sakura-jima on 14 and 20 July. During 15-18 July pilots observed ash plumes that rose to altitudes of 1.8-3.4 km (6,000-11,000 ft) a.s.l. and drifted NE, N, and NW. Plumes on 20 July rose as high as 2.1 km (7,000 ft) a.s.l. and drifted NW and N.

Based on pilot observations, the Tokyo VAAC reported that on 7 and 9 July ash plumes from Sakura-jima rose to altitudes of 1.8-2.7 km (6,000-9,000 ft) a.s.l. and drifted SE and NE. The VAAC also noted that the JMA reported explosions during 11-13 July.

Based on information from JMA, the Tokyo VAAC reported that during 30 June-1 July and 4-6 July explosions from Sakura-jima sometimes produced plumes. Those plumes, along with ash plumes occasionally seen by pilots, rose to altitudes of 1.5-4.6 km (5,000-15,000 ft) a.s.l. and drifted E and SE.

Based on information from JMA, the Tokyo VAAC reported that during 23-29 June explosions from Sakura-jima sometimes produced plumes. Those plumes, along with ash plumes occasionally seen by pilots, rose to altitudes of 1.8-3.7 km (6,000-12,000 ft) a.s.l. and drifted E, SE, and NW.

Based on information from JMA, the Tokyo VAAC reported that during 16-22 June explosions from Sakura-jima sometimes produced plumes. Those plumes, along with ash plumes occasionally seen by pilots, rose to altitudes of 1.2-3 km (4,000-10,000 ft) a.s.l. According to a news article, the JMA noted that two eruptions on 20 June brought the total number of eruptions in 2010 to 550, setting a new annual record. The total number of eruptions in 2009, the previous high at Sakura-jima, was 548.

Based on information from JMA, the Tokyo VAAC reported explosions from Sakura-jima during 12-14 June. Details of possible resulting plumes were not reported. On 15 June an ash plume at an altitude of 3 km (10,000 ft) a.s.l. was reported by a pilot.

Based on information from JMA and pilot observations, the Tokyo VAAC reported that on 3 June an eruption from Sakura-jima produced a plume that rose to altitudes of 2.1-3.4 km (7,000-11,000 ft) a.s.l. and drifted W.

Based on information from JMA, the Tokyo VAAC reported that during 4-6 and 8-9 May explosions from Sakura-jima often produced plumes. Those plumes, along with ash plumes occasionally seen by pilots, rose to altitudes of 2.1-3.7 km (7,000-12,000 ft) a.s.l. and sometimes drifted N, NE, E, and SE.

Based on information from JMA, the Tokyo VAAC reported that during 28 April-5 May explosions from Sakura-jima often produced plumes. Those plumes, along with ash plumes occasionally seen by pilots, rose to altitudes of 1.2-3.4 km (4,000-11,000 ft) a.s.l. and sometimes drifted NE, E, and SE.

Based on information from JMA, the Tokyo VAAC reported that during 14-26 April explosions from Sakura-jima sometimes produced plumes identified in satellite imagery. Those plumes, along with ash plumes occasionally seen by pilots, rose to altitudes of 1.5-3.7 km (5,000-12,000 ft) a.s.l. and sometimes drifted in multiple directions.

The Tokyo VAAC reported that during 7-13 April explosions from Sakura-jima sometimes produced plumes identified in satellite imagery. Those plumes, along with ash plumes occasionally seen by pilots, rose to altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l. and sometimes drifted NW, E, and SE.

The Tokyo VAAC reported that during 31 March-6 April explosions from Sakura-jima sometimes produced plumes identified on satellite imagery. Those plumes, along with ash plumes occasionally seen by pilots, rose to altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l. and drifted SW, SE, E, and NE.

The Tokyo VAAC reported that during 24-30 March explosions from Sakura-jima sometimes produced plumes identified on satellite imagery. Those plumes, along with ash plumes occasionally seen by pilots, rose to altitudes of 1.5-2.7 km (5,000-9,000 ft) a.s.l. and drifted SW, S, SE, and E.

The Tokyo VAAC reported that during 17-23 March plumes from Sakura-jima identified on satellite imagery, and ash plumes seen by pilots, rose to altitudes of 1.2-3 km (4,000-10,000 ft) a.s.l. and drifted SE and E.

Based on information from JMA, the Tokyo VAAC reported that during 10-16 March multiple explosions from Sakura-jima produced plumes that rose to altitudes of 1.2-2.7 km (4,000-9,000 ft) a.s.l. and drifted N, NE, E, and SE. Pilots reported that on 11 and 16 March ash plumes rose as high as 2.7 km (9,000 ft) a.s.l. and drifted SE and NE.

During 3-9 March, the Tokyo VAAC reported multiple explosions from Sakura-jima based on information from JMA. During 3, 5-6, and 8-9 March, plumes rose to altitudes of 1.5-2.4 km (5,000-8,000 ft) a.s.l. and drifted NE, E, and SE. Pilots reported on 8 and 9 March that ash plumes rose as high as 3 km (10,000 ft) a.s.l.

The Tokyo VAAC reported that during 24 February-2 March explosions from Sakura-jima produced plumes identified in satellite imagery and seen by pilots. The plumes, occasionally containing ash, rose to altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l. and drifted N, NE, E, and SE.

The Tokyo VAAC reported that during 17-23 February plumes from Sakura-jima identified on satellite imagery, and ash plumes seen by pilots, rose to altitudes of 1.5-4 km (5,000-13,000 ft) a.s.l. and drifted NE, E, SE, and S.

Based on information from JMA, the Tokyo VAAC reported that during 11-16 February multiple explosions from Sakura-jima produced plumes that rose to altitudes of 1.5-2.7 km (5,000-9,000 ft) a.s.l. and drifted N, E, SE, and S.

Based on information from JMA, the Tokyo VAAC reported that during 3-9 February multiple explosions from Sakura-jima produced plumes that rose to altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l. and drifted SE and N. On 5, 6, and 7 February, pilots reported that ash plumes sometimes drifted SE and S at altitudes of 1.5-3.4 km (5,000-11,000 ft) a.s.l. An eruption on 8 February produced an estimated 1-km-high lava fountain, and an ash plume with abundant lightning. Incandescent material fell onto the flanks.

Based on information from JMA, the Tokyo VAAC reported that during 27 January-2 February multiple explosions from Sakura-jima produced plumes that rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted SE, E, and NE. During 27-29 January and 1-2 February, pilots reported that ash plumes sometimes drifted SE and S at altitudes of 1.2-3 km (4,000-10,000 ft) a.s.l.

During 26 December 2009-9 January 2010, a visitor to Sakura-jima observed and photographed Strombolian and Vulcanian explosions from Showa crater. Based on information from JMA, the Tokyo VAAC reported that during 20-26 January multiple explosions often produced plumes that rose to altitudes of 1.2-2.4 km (4,000-8,000 ft) a.s.l. and drifted NE, E, SE, and S. On 23 January, a pilot reported that an ash plume drifted SE at an altitude of 1.8 km (6,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that during 13-19 January multiple explosions from Sakura-jima often produced plumes that rose to altitudes of 1.5-2.7 km (5,000-9,000 ft) a.s.l. and drifted SE and E. On 16 and 18 January, pilots reported that ash plumes drifted SE at altitudes of 2.4-3 km (8,000-10,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that during 6-12 January multiple explosions from Sakura-jima often produced plumes that rose to altitudes of 1.2-2.7 km (4,000-9,000 ft) a.s.l. and drifted SE and E. On 10 January a pilot reported that an ash plume drifted SE at an altitude of 3 km (10,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that during 30 December-5 January multiple explosions from Sakura-jima often produced plumes that rose to altitudes of 1.2-2.7 km (4,000-9,000 ft) a.s.l. and drifted NE, E, SE, and S. During 31 December-4 January pilots reported that ash plumes rose to altitudes of 2.4-5.5 km (8,000-18,000 ft) a.s.l. and drifted SE and E.

Based on information from JMA, the Tokyo VAAC reported that during 23-29 December explosions from Sakura-jima produced plumes that rose to altitudes of 1.5-2.7 km (5,000-9,000 ft) a.s.l. and drifted E, SE, and S. During 23-25 and 27 December, pilots reported that ash plumes rose to altitudes of 2.7-4.6 km (9,000-15,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that during 16-17 and 20-22 December explosions from Sakura-jima produced plumes that rose to altitudes of 1.5-2.4 km (5,000-8,000 ft) a.s.l. and drifted E, SE, and S. On 19 and 22 December, pilots reported that ash plumes rose to altitudes of 2.1-2.4 km (7,000-8,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 9-15 December produced plumes that rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted NE, E, SE, and S. On 14 December, a pilot reported that an ash plume drifted S at an altitude of 2.7 km (9,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 2-8 December produced plumes that rose to altitudes of 1.5-2.7 km (5,000-9,000 ft) a.s.l. and drifted in multiple directions. On 4 and 8 December, pilots 30-65 km S of Kagoshima airport reported ash plumes that rose to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted SW and NE.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima on 26 November and 1 December produced plumes that rose to altitudes of 1.8-2.7 km (6,000-9,000 ft) a.s.l. and drifted SW and E. Ash was seen in satellite imagery on 26 November.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima on 18 and 23 November produced plumes that rose to altitudes of 2.1-2.7 km (7,000-9,000 ft) a.s.l. and drifted S and E.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 11-13 and 15-17 November produced plumes that rose to altitudes of 1.5-2.4 km (5,000-8,000 ft) a.s.l. and drifted in multiple directions.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 4-10 November produced plumes that rose to altitudes of 1.8-2.7 km (6,000-9,000 ft) a.s.l. and drifted in multiple directions. Pilots reported ash plumes that rose to an altitude of 2.4 km (8,000 ft) a.s.l. on 5 November and to an altitude of 1.2 km (4,000 ft) a.s.l. on 9 November. Plumes drifted E and N, respectively. According to a news article, Sakura-jima exploded for the 400 th time in 2009 on 5 November.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 28 October-3 November produced plumes that rose to altitudes of 1.2-2.7 km (4,000-9,000 ft) a.s.l. Some plumes drifted W, SW, S, SE, and NE.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 21-22, 24-25, and 27-28 October produced plumes that rose to altitudes of 1.5-2.4 km (5,000-8,000 ft) a.s.l. Some plumes drifted W, SW, S, and SE.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 13-20 October produced plumes that rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted SW, S, SE, and E. On 15 October, a pilot reported that an ash plume rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted SE.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 7-12 October produced plumes that rose to altitudes of 1.2-2.7 km (4,000-9,000 ft) a.s.l. and drifted W, SW, S, and SE. An explosion was also detected on 13 October.

Based on information from JMA and pilot observations, the Tokyo VAAC reported that explosions from Sakura-jima during 30 September-6 October produced plumes that rose to altitudes of 1.8-4.3 km (6,000-14,000 ft) a.s.l. Plumes occasionally drifted E, N, and W.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 23, 25, and 27-29 September produced plumes that rose to altitudes of 1.8-2.7 km (6,000-9,000 ft) a.s.l. and drifted SW, W, and NW.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 16, 18-19, and 21 September produced plumes that rose to altitudes of 1.5-2.7 km (7,000-8,000 ft) a.s.l. and drifted S, SW, W, NW, and NE. A pilot reported ash on 19 September.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 9-15 September produced plumes that rose to altitudes of 1.5-2.7 km (5,000-9,000 ft) a.s.l. and drifted S, SE, and E.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 2-8 September produced plumes that rose to altitudes of 1.2-2.7 km (4,000-9,000 ft) a.s.l. and drifted W, SW, and S.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 26-29 August and 1 September produced plumes that rose to altitudes of 1.2-3.4 km (4,000-11,000 ft) a.s.l. Plumes occasionally drifted N, NE, and E. An explosion was reported on 31 August but no information about a possible resulting plume was reported.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 19-25 August produced plumes that rose to altitudes of 2.1-2.4 km (7,000-8,000 ft) a.s.l. Plumes occasionally drifted N, E, and SE. A pilot reported that on 24 August an ash plume rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted less than 20 km S.

Based on information from JMA, the Tokyo VAAC reported eruptions and explosions from Sakura-jima during 12-17 August. Plumes rose to altitudes of 2.1-2.7 km (7,000-9,000 ft) a.s.l. during 14-17 August and occasionally drifted E or N.

Based on information from JMA, the Tokyo VAAC reported that eruptions and explosions from Sakura-jima during 5-10 August produced plumes that rose to altitudes of 1.8-2.7 km (6,000-9,000 ft) a.s.l. Pilots reported that ash plumes rose to altitudes of 1.8-4 km (6,000-13,000 ft) a.s.l. during 7 and 9-10 August. Plumes drifted in multiple directions.

Based on information from JMA, the Tokyo VAAC reported that on 22 July explosions from Sakura-jima produced plumes that rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted E and SE. On 23 July and 27 July pilots observed ash plumes that rose to altitudes of 2.1 and 3 km (7,000 and 10,000 ft) a.s.l. and drifted E and SW, respectively. Explosions were reported during 24-25 and 28 July.

Based on information from JMA, analyses of satellite imagery, and pilot observations, the Tokyo VAAC reported that during 15-21 July explosions from Sakura-jima's Showa crater occasionally produced plumes that rose to altitudes of 1.8-2.7 km (6,000-9,000 ft) a.s.l. Plumes were observed drifting SW, N, and NE. On 19 July, JMA raised the Alert Level from 2 to 3 (on a scale of 1-5). They noted increased frequency of explosive eruptions since late June, and shock waves that were detected on 18 and 19 July.

Based on information from JMA, the Tokyo VAAC reported that during 8 and 10-15 July explosions from Sakura-jima sometimes produced plumes that rose to altitudes of 1.8-3.4 km (6,000-11,000 ft) a.s.l. The plumes drifted NE and E.

Based on information from JMA, the Tokyo VAAC reported that during 2-4 and 6-7 July explosions from Sakura-jima sometimes produced plumes that rose to altitudes of 2.1-2.7 km (7,000-9,000 ft) a.s.l. The plumes drifted N, NE, E, and SE.

Based on information from JMA, the Tokyo VAAC reported that during 24-30 June explosions from Sakura-jima sometimes produced plumes that rose to altitudes of 2.1-3.4 km (7,000-11,000 ft) a.s.l. The plumes drifted NE, E, and S.

Based on a pilot observation, the Tokyo VAAC reported that on 12 June an ash plume from Sakura-jima rose to an altitude of 1.8 km (6,000 ft) a.s.l. The JMA reported that during 14-16 June eruptions produced plumes that rose to altitudes of 2.4-2.7 km (8,000-9,000 ft) a.s.l. Plumes drifted SE and E on 14 and 15 June.

Based on information from JMA, the Tokyo VAAC reported that on 7 June an eruption from Sakura-jima produced a plume that rose vertically to an altitude of 3 km (10,000 ft) a.s.l. An eruption on 9 June resulted in a plume that rose to an attitude of 2.4 km (8,000 ft) a.s.l. and drifted N.

Based on information from JMA, the Tokyo VAAC reported that on 30 May an explosion from Sakura-jima produced a plume that rose to an altitude of 4.6 km (15,000 ft) a.s.l. and drifted SE. On 31 May, an ash plume rose to an altitude of 3 km (10,000 ft) a.s.l. The next day, eruptions produced plumes that rose to altitudes of 2.1-3.4 km (7,000-11,000 ft) a.s.l. Some plumes drifted S.

Based on information from JMA and pilot observations, the Tokyo VAAC reported that on 9 May eruptions from Sakura-jima produced plumes that rose to altitudes of 2.1-3 km (7,000-10,000 ft) a.s.l. and drifted S. On 12 May, an ash plume drifted E at an altitude of 1.8 km (6,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that on 8 April an eruption from Sakura-jima produced a plume that rose to an altitude of 2.7 km (9,000 ft) a.s.l. JMA reported that on 9 April a Vulcanian explosion from Showa crater on the E flank ejected bombs as far away as 1.3 km. A plume rose to an altitude of 4.8 km (15,700 ft) a.s.l. and drifted SW; JMA stated that the plume altitude was the highest altitude a plume reached since June 2006. A pyroclastic flow traveled 1 km E. According to a news article, heavy ashfall was reported in Kagoshima City (about 10 km W), the first ashfall reported there since October 2002. On 10 April, the Tokyo VAAC reported that eruptions produced plumes that rose to altitudes of 2.1-2.7 km (7,000-9,000 ft) a.s.l. and drifted W and S.

Based on information from JMA, the Tokyo VAAC reported that during 5-7 April explosions and eruptions from Sakura-jima produced plumes that rose to altitude of 2.1-3 km (7,000-10,000 ft) a.s.l. Plumes drifted SE on 5 April and S on 7 April.

Based on information from JMA, the Tokyo VAAC reported that an explosion from Sakura-jima on 26 March produced a plume that rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted SE. JMA reported occasional weak eruptions during 27-30 March.

On 14 March, JMA reported two Vulcanian explosions from Sakura-jima to heights of 400-500 m above an unspecified crater; ejected bombs landed as far away as 800 m. Both the summit crater and Showa crater on the E flank had recently been active. Based on information from JMA, the Tokyo VAAC reported that an eruption on 17 March produced a plume that rose to an altitude of 2.1 km (6,000 ft) a.s.l. and drifted E.

During 7-10 March, JMA reported that 12 Vulcanian explosions occurred from Showa Crater, on the E flank of Sakura-jima. Some explosions were seen from JMA's Kagoshima Observatory; observers reported that ejected bombs landed as far away as 800 m from the crater and plumes rose to an altitude of 2.9 km (9,500 ft) a.s.l. Based on information from JMA, the Tokyo VAAC reported that an eruption on 7 March, and explosions during 8-10 March, produced plumes that rose to altitudes of 1.8-2.7 km (6,000-9,000 ft) a.s.l. Plumes drifted N and S during 8-10 March. [Correction: Ejected bombs landed as far away as 1,800 m from the crater.]

Based on information from JMA, the Tokyo VAAC reported explosions from Sakura-jima during 28 February-1 March. On 1 March, plumes rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l. and drifted S. JMA raised the Alert Level from 2 to 3 (on a scale of 1-5). During 1-2 March, three Vulcanian explosions occurred from Showa Crater, ejecting bombs that landed as far away as 1.3 km on 2 March. Deformation was also detected. The Tokyo VAAC reported that eruptions or explosions produced plumes that rose to altitudes of 2.7-3 km (9,000-10,000 ft) a.s.l. on 2 and 4 March, and an explosion occurred on 3 March.

JMA lowered the Alert Level for Sakura-jima from 3 to 2 (on a scale of 1-5) on 19 February because deformation was absent, seismicity was low, and no eruptions occurred after 5 February. Based on information from JMA, the Tokyo VAAC reported that on 22 February an explosion produced a plume that rose to an altitude of 2.7 km (9,000 ft) a.s.l. and drifted N.

JMA reported that Sakura-jima erupted explosively eight times during 1-2 February; bombs were deposited as far away as 800 m from the Showa crater (on the E slope of Minami-dake, or "south mountain," at an elevation of about 800 m). JMA raised the Alert Level from 2 to 3 on 2 February. Based on information from JMA, the Tokyo VAAC reported that during 4-5 February explosions and eruptions produced plumes that rose to altitudes of 2.1-2.4 km (7,000-8,000 ft) a.s.l. and drifted SE. On 9 February a pilot reported that an ash plume rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted SE.

Based on information from JMA, the Tokyo VAAC reported that during 28 January and 1-3 February explosions and eruptions from Sakura-jima produced plumes that rose to altitudes of 1.8-3.4 km (6,000-11,000 ft) a.s.l. and drifted SE, S, and SW.

Based on information from JMA, the Tokyo VAAC reported that during 12-13 June explosions from Sakura-jima produced ash plumes to an altitude of 3.4 km (11,000 ft) a.s.l. The plumes drifted NW, NE, and SW.

Based on information from JMA, the Tokyo VAAC reported that on 9 June eruption plumes from Sakura-jima rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted S. Explosions were reported on 10 and 11 June.

Based on information from JMA, the Tokyo VAAC reported that on 22 May an eruption plume from Sakura-jima rose to altitudes of 2.4 km (8,000 ft) a.s.l. and drifted NE. An explosion was reported on 24 May.

Based on information from JMA, the Tokyo VAAC reported that during 15-21 May eruption plumes from Sakura-jima rose to altitudes of 1.8-3.4 km (6,000-11,000 ft) a.s.l. The plumes drifted N, NE, SE, S, and SW.

Based on information from JMA and observations of satellite imagery, the Tokyo VAAC reported that during 6-7 May eruption plumes from Sakura-jima rose to altitudes of 2.4-3.4 km (8,000-11,000 ft) a.s.l. The plumes drifted S.

Based on pilot reports and observations of satellite imagery, the Tokyo VAAC reported that an ash plume from Sakura-jima rose to an altitude of 4.6 km (15,000 ft) a.s.l. and drifted 100 km E on 19 April. The next day, the JMA reported that a plume rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted SW.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 11-15 April produced plumes that rose to altitudes of 2.1-3.4 km (7,000-11,000 ft) a.s.l. and drifted SW, NE, and SE.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima on 6 February produced plumes that rose to altitudes of 1.2-2.1 km (4,000-7,000 ft) a.s.l. and drifted SE. Ash was not detected on satellite imagery.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima on 3 February produced plumes that rose to altitudes of 1.5-2.7 km (5,000-9,000 ft) a.s.l. and drifted SE. Ash was not detected on satellite imagery. On 5 February, a pilot reported an ash plume at an altitude of 2.1 km (7,000 ft) a.s.l.

Based on information from JMA, the Tokyo VAAC reported that eruption plumes from Sakura-jima rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted N during 20-21 June. Ash was not detected on satellite imagery.

Based on information from JMA, the Tokyo VAAC reported that ash plumes from Sakura-jima rose straight up to an altitude of 2.1 km (7,000 ft) a.s.l. on 8, 10, and 11 June. The 10 June plume drifted S. Ash was not detected on satellite imagery.

Based on information from JMA, the Tokyo VAAC reported that ash plumes from Sakura-jima rose straight up to altitudes of 2.1-2.4 km (7,000-8,000 ft) a.s.l. during 31 May-1 June. During 4-5 June, plumes again rose to the same altitudes as during 31 May-1 June and drifted W, NW, and E. Ash was not detected on satellite imagery.

Based on information from JMA and a pilot report, the Tokyo VAAC reported that ash plumes from Sakura-jima rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. during 23-24 and 26-28 May. Plumes drifted E and SE and rose straight up.

Based on information from JMA and a pilot report, the Tokyo VAAC reported that ash plumes from Sakura-jima rose to altitudes of 1.2-2.7 km (4,000-9,000 ft) a.s.l. during 16 and 20-22 May. Plumes drifted NW on 16 May and rose straight up during 20-22 May.

Based on information from Japan Meteorological Agency (JMA), the Tokyo VAAC reported an explosion from Sakura-jima on 10 February. The altitude and direction of a resultant plume were not reported. On 13 February, an explosion produced a plume that rose to an altitude of 2.1 km (7,000 ft) a.s.l.

Based on information from Japan Meteorological Agency (JMA), the Tokyo VAAC reported an eruption from Sakura-jima on 2 January. The resultant plume reached an altitude of 3.4 km (11,000 ft) a.s.l. and drifted SW.

Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima on 22 November produced eruption plumes that reached an altitude of 2.1 km (7,000 ft) a.s.l. and drifted W. On 26 November, plumes reached an unreported altitude.

Based on information from JMA, the Tokyo VAAC reported that eruptions at Sakura-jima on 3 and 4 September generated plumes that rose to ~2.7 km (~9,000 ft) a.s.l. and drifted mainly NW and N, respectively.

On June 10, the Sakura-jima Volcano Research Center reported an increase in low-frequency earthquakes since mid-March and in small tremors with a less than 2 minute duration since mid-May 2006. A thermal anomaly at the volcano grew in size after February 2006.

On 4 and 5 June, intermittent eruptions at Sakura-jima, from an upper E-flank vent, near or within the 1946 vent, produced ash clouds that reached unknown heights. No ash was visible on satellite imagery. This was the first reported Sakura-jima eruption from a vent outside the summit crater in 58 years. The 1946 vent was the source of major lava flows that reached the E and S coasts of the former island.

Based on information from JMA, the Tokyo VAAC reported that an explosion at Sakura-jima on 28 April produced an ash plume that rose to 2.1 km (7,000 ft) a.s.l. An explosion on 1 May produced a plume that rose to an unknown height.

Based on information from JMA, the Tokyo VAAC reported that an eruption occurred at Sakura-jima on 2 September at 0927. The resultant ash plume reached a height of ~2.1 km (7,000) ft a.s.l. and drifted NW.

Based on information from JMA, the Tokyo VAAC reported that explosions at Sakura-jima occurred on 15 May at 1107 and on 17 May at 1946, sending ash plumes to heights of ~1.8 km and 2.1 km a.s.l., respectively. A pilot reported ash on 18 May, at a height of ~1.2 km a.s.l., ~23 km S of the Amori region.

Based on information from JMA, the Tokyo VAAC reported that an eruption at Sakura-jima on 28 April at 1820 produced a plume to a height of ~2.4 km a.s.l. that drifted SE. No ash was visible on satellite imagery.

Based on information from the Japanese Meteorological Agency, the Tokyo VAAC reported that explosions at Sakura-jima on 26 March at 1715 and 27 March at 0607 produced plumes that extended S and rose to ~2.5 km a.s.l. and ~2 km a.s.l., respectively.

Surface observations from Kagoshima airport revealed that on 22 July an ash cloud from Sakura-jima rose to 2.1-2.4 km a.s.l. Ash was visible extending to the SW on satellite imagery. Ash was also observed on 23 July at an unknown altitude.

Information is preliminary and subject to change. All times are local (unless otherwise noted)

March 1969 (CSLP 26-69)

The following information is from the "Asahi," Tokyo, 9 March 1969. At 0742, 8 March, Minami-dake emitted smoke up to a height of 1,500 m. A large quantity of volcanic ash fell on tangerine orchards at the foot of the volcano and on Kagosima Airport on the opposite shore.

July 1970 (CSLP 60-70)

Lava mass observed in early May; explosion on 12 June

Card 0973 (15 July 1970) Lava mass observed in early May; explosion on 12 June

"A lava mass (about 100 m across) had appeared in the summit crater (Minamidake) . . . at the beginning of May, but activities of volcanic smoke emission and volcanic earthquakes did not exist. At 2031 JST on 12 June 1970, the crater exploded for the first time since the lava mass had been observed. This explosion was the third in this year. A small airshock was felt but the other phenomenon could not be observed owing to night time.

August 1970 (CSLP 60-70)

"Sakurazima volcanic explosion 7 July 1970, southern Kyushu, Japan. Minamidake, the summit crater of this volcano exploded at 0653 JST on 7 July 1970. Weak explosion-sound and airshock were observed. This explosion of the volcano is the fourth one this year."

Information Contacts:Y. Sawada, JMA.

September 1970 (CSLP 60-70)

Multiple explosions in August from Minamidake

Card 1009 (14 September 1970) Multiple explosions in August from Minamidake

"Sakurazima volcanic explosion 13, 19, and 30 August 1970, southern Kyushu, Japan. Minamidake, the summit crater, exploded at 0610 and 0939 JST on the 13th, 1214 JST on the 19th, and 1645 JST on the 30th of August. The state of the explosions at the crater could not be observed owing to clouds. This volcano had exploded eight times by August of this year."

Information Contacts:Y. Sawada, JMA.

October 1970 (CSLP 60-70)

Explosions on 6 and 10 September

Card 1031 (14 October 1970) Explosions on 6 and 10 September

Minamidake, the summit crater, exploded at 0151 JST on the 6th, 1138 JST on the 10th, and 0952 JST on the 19th of September. Explosions on the 6th and the 10th emitted great quantities of cinders on the middle flank of this volcano.

Information Contacts:Y. Sawada, JMA.

November 1970 (CSLP 60-70)

Large explosion on 14 October; significant activity in late October

Card 1057 (27 November 1970) Large explosion on 14 October; significant activity in late October

The new crater (W-crater) which had opened at Minamidake in August last year exploded at 1143 JST on 14 October 1970. Large quantities of volcanic smoke with a great explosive sound and roaring sounds were given out from the crater. Volcanic flame about 20 m across and 20-30 m high was observed at this crater during the night of 23 October and continued until 29 October. Smoke from the crater was given out until 30 October. Main summit craters (we call them A and B craters) at Minamidake have emitted out large quantities of volcanic smoke.

Information Contacts:Y. Sawada, JMA.

December 1970 (CSLP 60-70)

The summit crater of Minamidake (South peak) exploded at 0159 JST on the 12th, 2255 JST on the 15th, and 1147 JST on the 16th of November. The explosion on the 15th emitted volcanic smoke 1,000 m high, with the precipitation of cindering ash, an explosive sound and air shock. The explosion on the 16th emitted volcanic smoke 2,100 m high, with an explosive sound and air shock.

Information Contacts:Y. Sawada, JMA.

January 1971 (CSLP 60-70)

More December explosions; 19 total during 1970

Card 1095 (20 January 1971) More December explosions; 19 total during 1970

Summit crater, Minamidake, exploded at 0732 and 2352 JST on 16 December, 0428 on 20 December, 1401 JST on 21 December 1970. On the occasion of the explosion on 21 December, a large amount of volcanic smoke went up about 1,600 m high. In 1970, Sakurazima exploded 19 times in total.

Information Contacts:Y. Sawada, JMA.

February 1971 (CSLP 60-70)

Minamidake summit crater exploded at 1023 JST on 1 January and at 1457 JST on 11 January 1971. On the occasion of the latter explosion, a large quantity of volcanic smoke was given out which reached a height of about 3,000 m.

Information Contacts:Y. Sawada, JMA.

March 1971 (CSLP 60-70)

Explosions continue in February

Card 1156 (22 March 1971) Explosions continue in February

Three volcanic explosions at Minamidake summit crater occurred at 2128 JST on 14 February, at 1346 JST on 16 February, and at 0334 JST on 20 February, 1971. On the occasion of the explosion on 16 February, a large quantity of volcanic smoke (with a small amount of ash-fall went up to a height of about 1,800 m. Two other explosions took place at night and the details are unknown.

June 1971 (CSLP 60-70)

Four moderate explosions in April

Card 1226 (01 June 1971) Four moderate explosions in April

"Minamidake (south peak), summit crater of this volcano exploded at 2214 on 7 April, 0553 on 8 April, 2348 on 10 April, and 0333 on 29 April 1971. The details of these activities were unknown owing to night-time, but according to maximum amplitudes (25, 35, 28, and 18µ, respectively) of explosion earthquakes obtained by the seismograph installed at a point 5.4 km WNW of Minamidake, the intensities of these explosions were minor-to-moderate ones. On the occasion of the explosion on 8 April, a weak explosion sound and moderate air shock were felt. And, when the explosion on 10 April took place, 2,000-m-high volcanic smoke, a small amount of cinder-fall on the upper flank, weak air shock and weak explosion sound were observed."

Much smoke and ashfall. Volcanic thunder in rising smoke. Vegetable fields were damaged rather heavily by the ashfall.

14 Sep 1972

2244

--

Unknown (night-time).

15 Sep 1972

1108

3100

Much smoke. Cinders fell on the middle flank. Medium ashfall. One air shock was felt.

15 Sep 1972

1745

4000

Much smoke and ashfall.

Active emissions of volcanic smoke with ashfalls continued during 14 September. Explosions which occurred on 13 and 15 of September were some of the most remarkable ones in recent years. Many micro-volcanic earthquakes were registered, especially from 0600 on 14 September on three seismographs installed around this volcano; (e.g. 320 shocks from 0900 to 1400 and 60 shocks from 2100 to 2300 on 14 September). From interpretation of previous activities, elevation of the lava mass in the summit crater is experimentally expected.

October 1972 (CSLP 60-72)

Large explosion from Minami-dake on 2 October

Card 1463 (06 October 1972) Large explosion from Minami-dake on 2 October

"On 2 October [at] 1329 GMT, Minamidake crater "A" blew up with a terrific explosion (18th explosion this year). Rolls of volcanic thunder were heard twenty-three times. Volcanic ejecta (ash and pumice) fell within an area above 300 me altitude, but no lava flow took place. Air vibration of 3.5 millibars from the explosion was recorded on the biograph of the meteorological observatory of Kagoshima district. The maximum amplitude of vibration by explosion earthquake was 72 microns. The 1,070-m S peak of Sakurazima Island in Kagoshima Bay erupted twice early [on] 6 October, but there were no casualties. The eruptions registered a maximum amplitude of ten and fifteen microns at 0439 JST, and 0810am JST, respectively. The second eruption caused spewing up of rocks from the crater near the top of the peak. The eruptions were the 19th and 20th recorded this year. Earlier, the previous eruption that occurred on 2 October was the biggest since November 1957.

November 1972 (CSLP 60-72)

Frequent explosions in late October and early November, some to 4 km altitude

Card 1487 (15 November 1972) Details of September-October explosions

Minamidake summit crater exploded in September [once on the 13th, 14th, 21st, 25th, and 30th, and three times on the 15th]. Of these explosions, the explosion on the 13 September was a rather remarkable one. Volcanic smoke rose about 3,000 m high with heavy ashfalls. A wide area of vegetable fields was heavily damaged by the ashfall. Emission of a large quantity of smoke continued for about three hours and volcanic lightning was seen in the rising smoke. Some of the other explosions were also rather strong, and they were accompanied by cinders and ashfalls and much volcanic smoke (max. 4,000 m high). The appearance and rising of a lava mass in the summit crater is expected based on these activities and seismological observations by the Kagosima local Meteorological Observatory.

Minamidake exploded in October [on the 2nd (1), 6th (2), 27th (1), 28th (8), 29th (3), and 30th (1)]. During these explosions, emission of much smoke (sometimes 3,000-4,000 m high) was frequently observed. After the explosions in the early part of the month, felt earthquakes (intensity II on the JMA scale) took place, and before the explosions in the latter part of the month there were swarms of shallow micro-earthquakes. The explosions were accompanied by much volcanic smoke (max. about 4,000 m), explosion-earthquakes and cinder and ashfalls. Volcanic lightning and pillars of fire were also observed. The greatest explosion was the one on 2 October, one of the most remarkable ones over the past two or three years. It was greater than the explosion on 13 September. Many cinders fell onto the lower flank (max. 3 km from the crater) of this volcano, and these cinders caused forest fires on several parts of the middle flank. Pillars of fire caused by red-hot cinders were sometimes seen and volcanic lightning was frequently observed in the rising smoke. The air-shock from this explosion was felt even at Hitoyosi, 74 km NE of the volcano. Damage was less than that which occurred on 13 September.

Card 1488 (20 November 1972) Thirteen explosions during 1-5 November

Minamidake summit crater continued exploding in November [on the 1st (2), 2nd (3), 3rd (5), 4th (2), and 5th (1)]. During these explosions, a great deal of volcanic smoke with cinder and ashfalls rose to a maximum height of 4,000 m. Volcanic lightning and pillars of fire were sometimes observed in rising volcanic smoke. The greatest explosion of this series was the one at 1236 JMT on the first of the month. A great quantity of volcanic smoke with heavy ashfalls rose to 4,000 m, and many cinders fell down onto the middle flank, causing forest fires. During these activities, active emissions of volcanic smoke with ashfalls continued. After the explosion on 5 November, however, emission of volcanic smoke stopped. Many micro-earthquakes (shallow ones) registered on seismographs of the Kagosima Local Meteorological Observatory through 7 November.

January 1973 (CSLP 60-72)

Frequent explosions in November and December 1972

Card 1536 (17 January 1973) Frequent explosions in November and December 1972

On 16 November, active explosions at Minamidake summit crater resumed. From 16 November through 30 November, explosions took place 32 times. The total number of explosions in November was 45. Some of these were strong ones, with a great quantity of volcanic smoke (max. height: more than 3,000 m), red-hot cinder-falls onto the middle flank, pillars of fire (sometimes 200-300 m high), and resulting forest fires due to red-hot cinders. The amplitudes of some explosion-earthquakes registered with the JMA-59 type seismograph (magnification:100) at the Kagosima Local Meteorlogical Observatory (about 12 km W of the active crater) reached 40 microns in the explosions on 16 and 28 November. These amplitudes were large compared with the usual explosions. Around 18 November the so-called B-type volcanic earthquakes swarmed, and then, from 21 November, the frequency of explosions increased. [Explosions in the second half of November occurred on the 16th (1), 17th (1), 18th (2), 19th (1), 20th (1), 21st (3), 22nd (1), 23rd (3), 24th (7), 25th (3), 26th (1), 27th (1), 28th (6), and 30th (1).]

In addition to these explosions, remarkable emissions of volcanic smoke were sometimes observed. Explosions at Minamidake summit crater continued until the middle of December. Some of them were rather strong explosions, i.e. with great quantities of volcanic smoke (more than 3,000 m high), red-hot cinder-falls onto the middle flank, and resultant forest fires caused by red-hot cinders. The number of explosions in December was 28, and the total number in 1972 was 108. Large amplitudes of explosion-earthquakes (the maximum was 105 microns) were sometimes registered with the JMA-59 type seismograph at Kagosima Local Meteorlogical Observatory, and amplitudes of 30-60 microns were sometimes observed. These amplitudes show that the explosions were strong ones. [Explosions in December occurred on the 1st (5), 2nd (4), 3rd (1), 8th (1), 9th (3), 10th (3), 11th (3), 12th (4), and 13th (4).]

November 1973 (CSLP 139-73)

The Minamidake summit crater . . . has been quite active throughout most of 1973. In June, four explosions occurred on the first of the month, with smoke reaching an altitude of 5,000 m, and large quantities of cinders, ash, and lapilli being ejected. In July, explosions took place on the 17th and the 22nd. In August, there were a total of 17 explosions. On 18 and 19 August, the smoke reached an elevation of 4,000 m, and on 24 August 3,000 m. Activity increased significantly in September and October, with 14 explosions recorded in September (max. height of smoke was 3,000 m), and 36 explosions during the first 18 days of October. The explosion on 18 October was the 76th this year. The maximum height of the volcanic smoke was 3,500 m and 40 micron explosion-earthquakes were frequently recorded at the Kagosima Local Meteorlogical Observatory.

January 1974 (CSLP 139-73)

Frequent explosions in late November 1973

Card 1781 (23 January 1974) Frequent explosions in late November 1973

Emissions of volcanic smoke from Minamidake summit crater became active again on 27 November, and frequent explosions with detonations, air-shocks, and strong emissions of smoke (max. 4,000 m high) occurred (table 2). The explosions on 28 November ejected a great amount of lapilli to the southeast of the crater, and windshields of 15 cars driving on a road were broken by this ejecta. The total number of explosions in December was 31, and the total for the 1973 was 144.

Table 2. Number of explosions from the Minami-dake summit crater at Sakura-jima, 27 November-25 December 1974. Courtesy of JMA.

July 1974 (CSLP 88-74)

Number of explosions increases to 93 in June

Card 1886 (17 July 1974) Number of explosions increases to 93 in June

Recently, the Sakurazima volcano became quite active, and the occurrences of explosions increased. There were 93 explosions in June, and a total of 198 during the first six months of this year. Some of the explosions were accompanied by small to medium amounts of fragments ejected onto the flanks of the volcano, plus ashfalls and flame. The smoke generally reached heights of 2,000 m; the highest altitude reached was 3,300 m. According to the Kagosima Local Meteorlogical Observatory, the total amount of ash that fell in May was 133.5 grams/m2 at Kagosima city, about 10 km from the Minamidake summit crater of Sakurazima.

August 1974 (CSLP 88-74)

The activity of the Minamidake summit crater . . . is continuing. The total number of volcanic earthquakes recorded on the seismograph on the upper reaches of Mt. Sakurazima, and explosions at the Minamidake summit crater in July, were 26,069 and 49, respectively. Some of the explosions were accompanied by small to medium amounts of ejected fragments plus ash and flame. The smoke generally rose to heights of from 1,000-2,000 m with the highest being 3,000 m. About 2 cm of ashes fell at Sakurazima city, 5 km from Minamidake summit crater, and some ash reached Minamata city, about 70 km from Minamidake. Crops, such as mandarin oranges, vegetables, and mulberry trees were damaged considerably by the ashes.

During the summer of 1975 Sakura-jima was normally active. There were 16 explosions in September (figure 1). The highest eruption cloud reached a few thousand meters altitude.

Figure 1. Summary table of explosions from Minami-dake crater at Sakura-jima, October 1975-December 1976. Data courtesy of JMA. [October 1975-May 1976 data were added, and errors in the June 1976-December 1976 data have been corrected from the originally published material.]

Two notable explosions occurred during May. Volcanic activity had been increasing during 1976 and dark smoke had been frequently observed since an explosion on 7 April. On 13 May at 0738, an explosion sent a cloud to 2,000 m height. This moderate explosion was the 29th of 1976 at the Minami-dake summit crater.

Large amounts of pumice and lapilli fell onto the E slope of the crater. At Sakura-jima-guchi, 5.5 km ESE of the crater, up to 3 cm of pumice was deposited (as measured on a road), and maximum ejecta size was 25 x 25 x 4 cm. Automobiles and crops in the area were damaged by the ashfall.

On 17 May at 1342, an eruption cloud reached 2700 m height (not 16 miles as reported by UPI in the press) following the 31st and largest explosion recorded in 1976. Tiba reported blocks up to l m across falling 2.5 km from the vent. Shimozuru reported cinders 2-6 cm in size at Arimura, 3 km SSE of the crater. At Furusato, 3 km S of the crater, and at a school 7 km SE of the crater, window glass was broken by the strong airshock which measured 0.34 millibars on a microbarograph 10 km W of the crater. Volcanic tremor occurred 32-36 hours before this major eruption, then volcanic earthquakes continued up to 22 hours before its onset.

Both explosions took place at the newly-opened (since 10 December 1975) 40-m-diameter crater SE of crater A at Minami-dake. An estimated 170,000 tons of molten lava filled the bottom of crater A from 90 to 50 m depth.

An explosion at 0727 on 5 June deposited a small amount of lapilli (to 1 cm in diameter) at Kurokami, 5 km E of the crater. Maximum June ash cloud height exceeded 3000 m. Ashfalls were frequent during late June at Kagoshima City, 10 km W of the crater. Volcanic earthquakes occurred frequently. July explosions were small, but ash emission was heavy. The maximum height of ash clouds was 3000 m. Kagoshima City continued to experience frequent ash falls. The July 26th explosion occurred at 0357, producing a felt air shock. Vibrations continued to be felt after the explosion at Higashi-Sakura-jima, 3 km SSW of the crater.

Most of the explosions 10 September-28 October were small. [Ash cloud] emission was also observed, reaching a maximum of 3000 m [above the crater]. Volcanic earthquakes were frequent. The explosion at 1142 on 10 September deposited a large quantity of ash and lapilli at Kagoshima City. The 23 September explosion at 2015 was accompanied by a large detonation, an air shock, [an incandescent column], thunder, and rumbling. A large amount of ash and lapilli were deposited on the S flank, 3 km from the crater. Activity on 2 October began at 1238 and lasted about 3 hours, causing a heavy ashfall W of the vent. A large detonation and air shock were observed at 0028 on 6 October. This explosion caused a cinder fall on the middle flank.

Almost all 1 November-20 December explosions were small. Strong detonations, air shocks and [incandescent columns] were sometimes observed at the Kagoshima meteorological observatory. Emission of [ash] clouds, some of which rose 3000 m above the crater, was almost continuous, and ashfalls around the crater were frequent. At the time of one of these (21 October at 1228), a large quantity of ash moved down the W slope, but it was not possible to confirm it as a nuée ardente. On 4 November at 1700, an overflight revealed a red-hot lava mass [or mound] (40 m across) at the bottom of the summit crater. A weak [reflection of] glow, probably caused by the lava, was sometimes seen during October.

The explosion at 1632 on 31 January (figure 2) deposited a considerable quantity of lapilli [S of the crater]. At 1005 the next day, a strong air shock broke [65 windowpanes at a school in Tarumizu City, about 10 km SE of the crater]. After the l February explosions, [ash] emission from the crater ceased until 6 March [but white vapor emission continued from 2 February until the 6 March explosions]. The number of volcanic earthquakes decreased in February and March.

Ash clouds rose to a maximum of 2,800 m above the crater in August, but ashfalls were minor. Falling scoria from an explosion at 1317 on 29 August caused [grass fires at 8 points] on the SW flank. [The fires were extinguished in a few minutes.]

Explosion on 28 November breaks 60 windows in buildings on the S flank

Maximum ash cloud height during October was 2,500 m above the crater. Some incandescent material was ejected and reflected glow was occasionally observed. The air shock from an explosion at 0347 on 30 November broke [102 windowpanes] in villages about 3 km S of the summit. Tephra started grass fires, but these were quickly extinguished. No [injuries] resulted from the explosion, the 21st to occur in November.

Tephra from explosions at 1220 on 8 December, 1834 on 20 December, 0621 and 1507 on 22 December, and on 27 January, caused [grass] fires. A 300-m column of incandescent ejecta was observed at 0534 on l December, and reflected glow was seen between 0322 and 0325 on 10 December. The air shock from an explosion at 2140 on 8 December broke three [windowpanes] in a nearby village. Ash clouds rose 2,000 m above the crater on 6, 8, and 22 December.

Tephra from an explosion on 25 December cracked the windshield of an All Nippon Airways aircraft passing over the Hayato area, about 20 km NE of the crater.

Maximum January ash cloud height was 1,900 m above the crater on the 23rd. Incandescence, scoria ejection, air shocks, and rumbling accompanied the activity. Aerial observations in mid-January confirmed the continued growth of the lava mass present in the crater since September. Several earthquake swarms . . . were recorded during December and January.

February explosions were accompanied by air shocks and rumbling. Scoria from explosions at 0024 on 8 February and 0218 on 26 February caused [grass] fires. The maximum February cloud height was 1700 m above the crater, at 0850 on the 25th.

Powerful explosions from the summit crater of Minami-dake have become more frequent since summer 1977 (figures 2 and 3). Beginning in August, explosions have been preceded by earthquake swarms lasting several days. . . . This pattern has often occurred 4-5 times/month and has enabled scientists at the JMA's Sakura-jima Observatory to [forecast] the explosions. The frequent property damage that has occurred near the volcano since last summer continued in March and April. Many windowpanes and a car windshield were broken by airshocks and tephra during March. Incandescence was also observed during March and April.

The air shock from the 22 May explosion broke five windowpanes. Earthquake swarms . . . occurred in mid and late May, correlated with an increase in the number of explosions during the same period. A swarm of exceptionally long duration (16 hours) on 30 May was followed by four explosions on the 31st.

About 20 earthquakes . . . were recorded in June. . . . Consequently, JMA scientists believe that a large volume of magma remained on or just under the crater bottom in early June. Reuters reported a loud explosion on 21 July, producing a 1600-m eruption column, and two explosions on 23 July, throwing incandescent ejecta 2,500 m above the vent. UPI reported that strong winds from a typhoon spread about 2.5 cm of ash within 5 km of the summit after an explosion on 31 July.

During July, 25 explosions from the summit crater of Minami-dake were recorded. Large quantities of tephra (blocks, lapilli, and ash) were ejected by three explosions on 30-31 July. Strong [SE] winds from a typhoon carried the ejecta to [an inhabited area] 10 km [NW of] the crater. Three persons were slightly injured, and [windowpanes] were broken in 62 houses and 45 cars. More than 50 earthquake swarms, each lasting several hours, occurred during July. . . .

. . . [There were] 32 recorded explosions from the summit crater of Minami-dake during August. The explosions produced ash clouds that rose about 2,000 m above the crater. Emission of . . . ash clouds was continuous between explosions. Ash fell every day around the volcano, primarily to the NW, causing slight damage to crops, electric wires, and homes over a broad area. Total August ashfall was estimated at a few centimeters (20 kg/m2) in a village 5 km from the volcano.

The summit crater of Minami-dake exploded 25 times in September and 15 times in October. Since June, dense ash clouds have frequently been emitted from Minami-dake between recorded explosions. Ashfalls near the volcano were almost continuous June-October, damaging . . . crops, and impeding traffic. However, there was no damage from coarse tephra as in late July nor from explosion air shocks, which broke [windowpanes] in late May.

Only one explosion from the summit crater of Minami-dake was recorded during November, on the 15th. The ash ejection that had frequently occurred between explosions since the spring ended about 25 November. Activity has been limited to steam emission since then.

Further Reference. Kamo, K., 1979, The Recent Activity of Sakura-jima Volcano; in Report on Volcanic Activities and Volcanological Studies in Japan for the Period from 1975 to 1978; Bulletin of the Volcanological Society of Japan, v. 24, no. 4, p. 26-34.

Eleven explosions from the summit crater of Minami-dake were recorded in December. The number of explosions in 1978 was 231, little changed from 223 in 1977. Lapilli ejected on 4 December cracked 2 windshields of All Nippon Airways airplanes. Similar damage to aircraft above Sakura-jima occurred 8 April 1975 and 25 December 1977.

Fifteen explosions from the summit crater of Minami-dake were recorded during January (figure 4). On 5 January, lapilli broke [windshields] in seven cars. Ash emission was observed between explosions, but not as frequently as in the autumn of 1978.

Sixteen explosions occurred from the summit crater of Minami-dake during February. Ash emission between explosions remained infrequent, as it has since December. Yosihiro Sawada reports that high-amplitude volcanic tremor ended in November 1978, and shallow B-type earthquakes began to be recorded. An earthquake swarm in mid-December preceded the emplacement of a new incandescent lava [mound] on the [crater] floor of Minami-dake, after which explosions became more frequent.

Seven explosions from the summit crater of Minami-dake were recorded in April. Reflected glow was observed above the crater on 22 April. Earthquake swarms . . . were frequently recorded in April, indicating that the andesitic lava [mound] in the bottom of the crater was increasing in volume. The strongest explosions of the current eruption have taken place during periods when the lava dome was most voluminous.

No explosions from the summit crater of Minami-dake were recorded during May, the first time in 6 years that a month without explosions has occurred there [but see 4:9]. Sakura-jima's current eruption began in October 1955.

For the second consecutive month, no explosions from the summit crater of Minami-dake were recorded in June. The last explosions occurred on 30 April. Sakura-jima's current eruption has included several quiet phases, the most recent from December 1972 to April 1973.

The following is a report from Manabu Komiya. "Sakura-jima exploded on 19 August after 110 days of quiescence, producing an ash cloud 1 km high. It was the 46th explosion of this year. Five more explosions occurred in early September, but none caused any damage. The fact that no explosion had occurred in 110 days does not immediately suggest decreasing volcanism, because intermittent ash emission without explosive shocks had occurred through the explosion-free period, as frequently as before. Daily ash emission often caused ashfalls at cities and towns near the volcano. Volcanic gas that flowed down the flanks damaged vegetation, adding to the damage caused by falling ash. Reflected glow above the crater was often observed at night during July and early August. Swarms of B-type earthquakes . . . (one burst consisted of hundreds of earthquakes) were recorded a few times per month in June and August. These facts indicate that the lava mound on the crater floor persisted or grew during this period. An aerial inspection on 30 July revealed a large mound that had reached a volume of 7 x 103 m, twice that of May."

Explosions recorded at the JMA's Kagoshima Observatory, 11 km from Sakura-jima, were about twice as frequent in October and November as they were in September. Typically, an "explosion" consisted of a weak shock, registered both seismically and sonically, followed by ash ejection. Ash emission without an accompanying explosion occurred more often than the explosion-triggered events.

[The explosion at 1400 on 10 November was followed by about 20 minutes of tephra emission and continuous tremor.] Lightning was frequent in the tephra cloud, which deposited 2 cm of ash during a rainstorm at Furosato, 3 km from the crater. Lapilli cracked a car windshield and two cars collided after skidding on the wet ash.

The windshields of two domestic airliners were cracked as they flew into an eruption cloud near Sakura-jima at 0801 and 0805 on 18 November, about 20 minutes after a recorded explosion. In both cases, damage was restricted to the outermost of three sheets of glass, and the planes landed safely. Another 2 cm of ash fell at Furosato after this explosion.

Frequent explosions and ejections of dense ash clouds continued through December. Between 28 November and 28 December, 36 explosions were recorded at the JMA's Kagoshima Observatory. The 110-day explosion-free period of 1 May-18 August dropped the number of recorded explosions in 1979 to [149], from 231 in 1978 and 223 in 1977. However, the monthly totals for October-December 1979 are higher than the 1977-78 averages.

The windshield of a domestic YS-11 airliner was cracked by tephra at 1.5 km altitude at 1749 on 24 December, 9 minutes after an explosion from Sakura-jima. The plane landed safely at Kagoshima airport 7 minutes later.

Thirty-six explosions were recorded in December by the JMA's Kagoshima Observatory (table 3), bringing the total number in 1979 to 149. Tephra cracked airplane windshields on 18 and 24 December; both planes landed safely. In January, 10 explosions had been recorded by the 27th, none of which caused any damage.

Table 3. Explosions recorded at the Kagoshima Observatory, 19 August 1979-27 January 1980. Data courtesy of JMA.

Twenty explosions from Sakura-jima were recorded in February and 10 in March (figure 5), none of which caused any damage. Ash emission without explosions occurred less frequently in February and March than has been usual over the past 5 years.

Two bursts of B-type earthquakes were recorded in the 2-month period. About 1,000 events occurred in 11 hours on 13 February and about 500 in 5 hours on 15 March. Both of these bursts, thought by JMA geologists to be caused by magma rising in the vent, were followed by increased explosion activity. In addition, columns of incandescent tephra were ejected after the February earthquakes. On 14 February, two columns rose 200 m at 0438 and a 400-m column was ejected at 2137.

Activity beginning late 15 February was typical of the more prolonged eruptive periods that have characterized Sakura-jima since explosions resumed in August 1979. Soon after a loud explosion at 2241, two columns of incandescent tephra rose 200 m above the summit. Ejection of incandescent blocks was almost continuous until about midnight, then occurred every few minutes until 0110 on the 16th. Lapilli up to 3 cm in diameter fell on inhabited areas, but caused no damage. Much lightning was seen in the eruption clouds. Strong, continuous air vibrations rattled windows in towns at the base of the volcano. A seismograph recorded strong tremor until about 0100 on 16 February. By about 0300, eruptive activity had declined, and vapor emission or weak ash ejection continued until the 9 March explosion.

A total of 48 explosions from Sakura-jima were recorded in April, the largest monthly figure in 5 years. Frequent explosions continued into early May. Four of the April explosions produced ash clouds higher than 2 km, and two ejected incandescent columns. No damage was reported.

The period of unusually frequent explosions at Sakura-jima that began in late March ended on 7 June. In May, 69 explosions were recorded, the third highest monthly total since the eruption began in October 1955. Most of the May and June explosions produced ash clouds that rose 1-2 km above the crater; the highest clouds were 2.5 km on 17 May and 2.7 km on 7 June. A 100 m-high incandescent column was observed at night on 1 May.

Ash emission without an explosion [shock] has also more frequent than usual from late March through early June. Ash often fell on Kagoshima, causing various minor disruptions. Fallen ash derailed a streetcar on 2 May, and electric power for 3,700 homes was cut off on 8 May after wet, sticky ash caused numerous short circuits. During a heavy rainfall on 12 May, a debris flow damaged a concrete bridge at the foot of the volcano. Ash emission declined in mid and late June.

After a decline from 69 explosions in May to 12 in June, activity remained at a similar level until late July, when explosions became stronger and more frequent. The last July explosion was also the month's largest. A tephra cloud rose about 3 km, and [blocks fell onto] the lower half of the volcano. Ash fell to the NE, reaching [the city of] Miyakonojo, 40 km away, one hour after the explosion. No damage was reported.

The number of recorded explosions increased from 16 in July to 34 in August. The highest August eruption cloud rose 2 km above the summit, on the 2nd. Ash frequently fell NE of the volcano but no damage was reported. . . .

During September, 21 explosions were recorded. The highest September ash cloud rose 1800 m on the 7th. Blocks fell on the flanks on several occasions. A 200-m-high incandescent column lasted for 10 seconds on 30 September. No damage was reported from the September activity.

The number of recorded explosions declined from 21 in September to four in October, then increased to 21 in November. The highest October ash cloud reached 2.0 km, on the 1st. None of the October activity caused any damage. Lapilli from the largest November tephra cloud, which rose 2.5 km on the 8th, broke five car windshields. The air shock from the 28 November explosion broke two [windowpanes] in a hotel at the base of the volcano. No injuries were reported.

Explosions from the summit crater of Minami-dake were continuing at the end of 1980. The nine explosions in December brought the year's total to 276, the largest number since 362 were recorded in 1974. The highest December ash cloud rose 1.8 km on the 3rd. Airshocks and tephra fall from the explosions broke [windowpanes] in buildings, automobiles, and aircraft; disrupted traffic; and interrupted electric power on occasion in 1980; but caused no injuries.

A burst of B-type earthquakes that began at 0200 on 18 January prompted the JMA observatory at Sakura-jima to issue an explosion warning at 0930. Reflected glow was seen over the summit that night. Four strong explosions occurred during the next two days (figure 6). Each of the first three produced a 200-m-high incandescent column. The fourth, strongest explosion at 1632 on 20 January ejected an incandescent block that formed a 1.3-m-diameter crater when it fell near an inhabited area. Similar occurrences of B-type earthquake bursts, reflected glow of the lava mound in the crater, and explosions were observed in July and August 1979. None of the January explosions caused any damage.

Eleven explosions occurred in March. The highest ash cloud grew to 2 km on the 18th. Two incandescent columns rose simultaneously from vents in the summit crater of Minami-dake on the 20th. No damage was reported.

After only two explosions from the summit crater of Minami-dake had occurred in April, none were recorded in May until the 18th. As of 28 May, four explosions had occurred. The largest produced a 1.2-km-high ash cloud on the 24th. Although explosive activity was limited in April and May, there was continued ash ejection during which explosions were not registered at the JMA's Kagoshima Observatory. Bursts of B-type earthquakes were recorded on 3, 5, 18, and 19 May.

During the first 27 days of July, only one explosion from the summit crater of Minami-dake was recorded by the JMA's Kagoshima Observatory. Ash ejection without recorded explosions and local seismicity also remained at low levels through July. Activity since January 1978 is summarized in figure 7.

Figure 7. Activity at Sakura-jima during January 1978-June 1981, showing monthly number of recorded explosions (A), large ash clouds (B), recorded earthquakes (C), days when ashfall was observed at the Japan Meteorological Agency's Kagoshima Observatory, (D, black bars), and monthly volume of ash at Kagoshima Observatory (D, white bars). Ashfall is measured in a tray at Kagoshima Observatory. Explosions are counted by visual observation, microbarographs, and seismometers. Courtesy of JMA.

The decline in activity first noted in April reversed in August, when 34 explosions were recorded. Only one was recorded in July. Most of the explosions were small. The largest eruption cloud reached 2.5 km on 26 August. Ash frequently fell NE of the volcano, but no damage was reported. Weak glow was seen above the active crater on 13, 24, and 31 July.

Frequent explosions from the summit crater of Minami-dake continued through September, after increasing from one in July to 34 in August. None of the 38 recorded in September caused any damage. Ash clouds higher than 2 km above the summit were observed on 13, 14, 18, 20, and 23 September. On the 13th an ash cloud that rose to 2.6 km was ejected simultaneously with [dense powder] that covered a 100 x 100 m area on the W slope of the active crater. The highest cloud rose to 2.7 km, also on the 13th.

Frequent explosions continued through October, when 35 were recorded. Two 100-m-high incandescent columns were recorded for 3 seconds at 0444 on 2 October. Ash clouds higher than 2 km above the summit were observed on 3, 17 and 31 October.

Eruptive activity intensified in November. Explosions became more frequent and stronger; 50 were recorded. The explosion rate had been about 35/month August-September, but fewer than 4/month April-July. An explosion at 1528 on 16 November ejected incandescent tephra that caused [grass fires] on the SW flank. The [eruption] column rose 3 km, the greatest height this year. Lapilli from an explosion at 1322 on 21 November broke windshields on a few cars passing 3 km S of the summit crater of Minami-dake. Incandescent columns were observed on several occasions: 100 m high for 5 seconds on 7 and 22 November, and for 3 seconds on 14 and 29 November; 200 m high for 3 seconds on 30 November.

The rate of explosive activity at the summit crater of Minami-dake dropped slightly in December; 27 explosions had been recorded by the 25th. Incandescent columns 200 m high were observed for 7 seconds at 1836 on 9 December and for 5 seconds at 0622 on 22 December. Ash clouds higher than 2 km were observed on 3, 4, and 9 December.

Since last August, explosions from the summit crater of Minami-dake have been frequent. In January, 27 explosions were recorded (figure 8). A 200-m-high incandescent column lasting 3 seconds was observed on 20 January, and another 300 m high for 5 seconds on the 21st.

The rate of explosions from the summit crater of Minami-dake declined in early and mid-February, then increased late in the month. Frequent explosions continued through March. Recorded explosions numbered 15 in February, 47 in March.

On 26 February, an explosion at 1044 produced a 1,600-m-high eruption column, then a continuous ash cloud was observed until 1150, and from 1430 until sunset ended visual observation from the JMA's Kagoshima Observatory. A 1,500-m-high eruption column was ejected at 1731. On 28 February a continuous ash cloud was observed 0620-1230, and three explosions were recorded the next day. On 24 March a 100-m-high incandescent column was observed for 15 seconds, and on the 28th a 200-m-high incandescent column lasting 30 seconds was accompanied by rumbling. Local seismicity was active in the first half of February, when explosive activity had declined. JMA scientists have observed that a swarm of B-type earthquakes, which they interpret as possibly caused by magma rising to a shallower depth, is often followed by increased explosive activity. In March local seismic events and continuous ash clouds were frequently observed, but only rarely did an explosion with a large amount of ejecta occur. There was some damage to nearby farm products.

Recorded explosions declined from 47 in March to 15 in April. Ash clouds higher than 2,000 m were observed on 12 and 19 April. These two explosions ejected incandescent blocks, but no damage was reported. In February and March, volcanic gas . . . damaged farm crops at the SW foot of the volcano.

The number of recorded explosions from the summit crater of Minami-dake was 24 in May. After mid-May, most explosions ejected incandescent tephra, but no damage was reported. In late May activity gradually changed to continuous ash ejection without recorded explosions. Wind carried ash toward the W, causing heavy ashfall in and around the city of Kagoshima, on 25-26 May. The explosion on 19 May, at 0727, produced an eruption column higher that 2,500 m and was associated with 30 seconds of rumbling. Incandescent columns were observed on several occasions: 400 m high for 8 seconds on 4 May; 200 m high for 3 seconds on 5 May and for 5 seconds on 24 May.

The number of explosions from the summit crater of Minami-dake increased from [24] in May to 34 in June. A 300-m-high incandescent column was observed at 2223 on 8 June, and the highest plume rose 3000 m above the summit on 10 June. Carried by a strong wind, ejecta from the explosion at 0325 on 14 June fell in the area between Kurokami (4.7 km E of the crater) and Sakura-jima-guchi (5.5 km SE). At Kurokami, lapilli broke a car windshield and a building's windowpane.

Thirteen explosions were recorded in July. Activity was low during the first half of the month, then increased 16-24 July. A debris flow [caused by rainfall] carried away a concrete bridge at the S base of the volcano on the 24th. After the 24 July explosion, activity changed to continuous ash ejection without explosion [shocks].

In August, 14 explosions were recorded. Activity continued at the July level. On 24 August, continuous ash ejection without explosion [shocks] began in the morning, causing heavy ashfall to the NW. Ashfall from 1415-1500 was measured at 285 g/m2 at the JMA's Kagoshima Observatory (about 10 km W of the crater). At the Kagoshima Prefecture Office, 2 km N of the JMA Observatory, 5522 g/m2 of ash fell from 0900-1600. The ejection declined in the evening. The ash caused slight damage.

Explosive activity at the summit crater of Minami-dake and local seismicity have declined since September. Two explosions were recorded in September, 6 in October, and 4 in November. An explosion at 1130 on 17 September was followed by continuous ash ejection, without explosion [shocks], lasting for 98 minutes and resulting in heavy ashfall on the S half of the city of Kagoshima, about 15 km NW. In October, ash ejection occurred every day, although few explosions were recorded. The frequent ash ejection was accompanied by an increase in the number of recorded tremor events, which totaled 334 hours in October.

Each of the November explosions produced lapilli ejection, air shocks, and sounds. At 1523 on 23 November, the largest explosion of the 3-month period sent an eruption cloud to 3 km. The cloud was observed from the JMA's Miyakonojo Weather Station, 45 km ENE. An Air Nauru jet carrying 39 passengers and flying at about 3 km altitude entered the cloud 23 km ESE of Sakura-jima at 1545, 6 minutes after leaving Kagoshima Airport. The impact of the lapilli produced hairline cracks in three cockpit windows, prompting the pilot to return to Kagoshima, where he landed safely. At the SE foot of the volcano, a car windshield was destroyed.

Explosive activity at the summit crater of Minami-dake intensified in December when 32 explosions were recorded. Only 12 had been recorded from September through November. Ash ejections lasting less than 25 minutes and not accompanied by instrument-recorded explosions were frequently observed. Although eruptive activity was frequent, large amounts of ejecta were rarely observed. No damage was reported. In early December, 124 hours of volcanic tremor were recorded but only 20 hours were recorded during the middle of the month, when explosive activity peaked.

Activity at the summit crater of Minami-dake intensified in January; 54 explosions (figure 9) and 35 ash ejections not accompanied by instrument-recorded explosions were observed. In the second half of January, explosions were accompanied by larger amounts of lapilli. An explosion at 1059 on 26 January (table 4) ejected an eruption column that rose 3.8 km above the summit, the highest observed in the past 9 years. This cloud was large enough to be observed from JMA's Asosan Weather Station, 150 km to the NNE; aircraft crews reported that it rose 7.8 km above sea level. Lapilli from this explosion broke the windshield of a car passing near Arimura, 3 km S of the summit. Incandescent columns were observed during two of the explosions on 31 January. A 300-m-high column accompanied the explosion at 0228 and lasted 40 seconds; a column 200 m high lasted 30 seconds during the 0545 explosion.

The rate of explosions at the summit crater of Minami-dake has gradually increased since December. In January, 53 were recorded and in February, 73 explosions were recorded, one of the larger monthly totals since the eruption began in 1955.

Ashfall and eruption clouds were observed on 11, 14, and 27 February at Miyakonojo Observatory. The air shock from the explosion at 2241 on 5 February was large enough to be felt at Miyazaki Observatory, 80 km NE. On 18 February a hut at Arimura, 3 km SSE of the summit, was set on fire by an incandescent block, 50-100 cm in diameter. The explosion at 1043 on the 21st was not large enough to be accompanied by any observed explosive sound or felt air shock at Kagoshima Observatory but strong NW winds carried lapilli toward the SE foot of the volcano where 4 car windshields were cracked or broken. Two incandescent columns, rising about 200 m above the crater, were observed in February for 10 seconds on the 1st, and for 5 seconds on the 27th.

Rain on 2 February triggered debris flows in S flank valleys. One flowed into nine houses and a hotel after pushing away a 10-m-long sand-trap wall, and covered the adjacent road for about 50 m. The monthly number of recorded seismic events was 4,456 in January, but decreased to 2410 in February.

The number of recorded explosions from the summit crater of Minami-dake declined to [36] in March and 22 in April. Observers saw lapilli ejected by about 1/4 of the explosions in March and 1/3 in April, but no damage was reported. The monthly number of recorded seismic events, including tremors, was 1,358 in March and 768 in April. On 2 March, rain-triggered debris flows in S and E flank valleys temporarily blocked a road.

The number of explosions from the summit crater of Minami-dake recorded in May was 22, the same as in April. In the second half of May, most of the explosions ejected lapilli and sent ash and vapor to more than 2 km above the summit. The 4.4-km-high [eruption] column from an explosion at 1320 on 18 May was one of the largest since the eruption began in 1955. On 22 May an explosion at 1237 that sent a column to more than 4 km was followed by 2 hours of continuous ash and vapor ejection. The activity was accompanied by thunder and temporary interruption of electric and telephone service. Ash fell as far as Aburatsu, on the E coast of Kyushu, 70 km E of the volcano. An explosion on 26 May was also accompanied by continuous ash ejection. A large amount of ash fell SSE of the volcano; more than 20 car windshields were broken, and the roof of a primary school cracked.

In June, 33 explosions were recorded from the summit crater of Minami-dake and 31 in July. Although the explosion rate from June to mid-July was above its usual level, rarely was a large amount of ejecta observed in any explosion. Only about 1/8 of the explosions ejected much lapilli, or produced eruption columns that rose to more than 2 km above the summit.

Activity intensified slightly 19-24 July. Most explosions produced large amounts of ejecta and ash frequently fell on the cities of Miyakonojo (40 km ENE) and Miyazaki (80 km NE). The end of explosive activity on 25 July was followed by continuous ash ejection. Bad weather limited visual observation, but volcanic tremor that was assumed to be accompanied by ash ejection was recorded until 29 July. The number of large B-type earthquakes suddenly increased at about 1800 on 29 July and remained high until 0300 the next day. Earthquake size then returned to its usual level, but the recorded events were still more numerous than usual.

Explosive activity resumed on 31 July, accompanied by a decrease in seismic activity. An explosion at 1445 on 2 August ejected large amounts of lapilli, which fell near Kyoto University's Sakura-jima Volcano Observatory (about 1.7 km SW of the summit) and the site of sand trap wall construction, where 1 worker [originally reported as 4] was slightly burned. [Blocks] made many craters [near the University Observatory and the construction site]; the largest was 1.5 m in diameter and 1 m deep [produced by a block 50 cm in diameter].

Recorded explosive eruptions from the summit crater of Minami-dake were frequent in August [33] and September (36), fewer in October (21) and November (16). In mid-August strong wind carried a large amount of ejecta to the inhabited area around the volcano, damaging cars and houses. On 14 August lapilli as large as 6-7 cm in diameter fell on Nojiri, at the foot of Sakura-jima 4 km SW of Minami-dake, breaking or cracking windshields on 16 cars, a house windowpane, and the roof of a hut. Radio news from Kagoshima reported that windshields on three cars were cracked by lapilli as large as 1-3 cm in diameter at Tarumizu Wharf, on the S side of the city. An explosion at 0153 on 16 August scattered lapilli up to 2.5 cm in diameter between Mochiki and Yumoto (3.5 km SSW of Minami-dake), where windshields on 26 cars ware cracked.

Explosive activity remained at a high level in September. Incandescent blocks from an explosion at 1148 on 12 September started a flank [brush] fire. A heavy ashfall on 17-18 September deposited 270 g/m2 of ash at JMA's Kagoshima Observatory (table 5); a Kagoshima streetcar derailed on 19 September due to ash on the tracks. A large air shock from an explosion at 1518 on 20 September broke windows in Kagoshima, and another explosion at 1638 sent lapilli as large as 1 cm in diameter toward the N. Five debris flows moved down S flank valleys on 1, 10, 20, and 21 September. Bursts of discrete seismic events were frequent in September. Bursts on 19 and 28 September lasted for about 10 hours and included large events.

Recorded explosive eruptions were fewer in October (21) and November (16), but about as frequent in December (37) as in August [33] and September (36). About 1/4 of October's explosions were accompanied by large quantities of ejecta. On 10 October, the last and strongest of explosions at 1001, 1131 and 1351 sent an eruption column to 2.5 km above the summit. A large amount of lapilli broke windshields on two cars at Nojiri and Mochiki, at the SW foot of the volcano about 4 km from the summit. Activity remained at a relatively low level from late October to mid November. In late November stronger explosions were again frequently observed. During the first 12 explosions in December, observers at the Kagoshima Observatory witnessed lapilli ejection. Ejecta from an explosion at 1702 on 7 December broke a windshield at Usine in Tarumizu City (10 km SSE). 0n 13 December an explosion at 1028 generated an air shock that broke five windows in a hotel and one in a house. There were 413 recorded explosions in 1983, the second largest annual total since the current eruption began in 1955.

An explosion at Sakura-jima on 12 April at about 0940, the 95th in 1984, produced an eruption cloud that rose to 2.3 km (table 6). According to press reports, ejecta fell over half the volcano and broke windows at the foot.

Table 6. Damage caused by Sakura-jima eruptive activity in 1984.

Date

Time

Result

04 Jan 1984

1928

Lapilli broke car windshield at S foot of the volcano.

10 Jan 1984

1457

Air shock cracked a window at E foot.

11 Jan 1984

2140

Air shock cracked three windows.

08 Mar 1984

0724

Lapilli cracked car windshield.

19 Mar 1984

--

Debris flows reached E foot; no damage reported.

30 Mar 1984

1853

Large quantity of lapilli; forest fires started.

12 Apr 1984

0941

Strong air shock cracked three windows at the E and S foot, two windows in Kagoshima.

19 Apr 1984

--

Debris flows occurred.

29 Apr 1984

1800

Large quantities of incandescent ejecta started forest fires in more than 10 places; strong air shock broke a window in Kamoike. (Damage in Kagoshima is rare.)

04 May 1984

--

A windowpane was broken in Yasui.

08 May 1984

--

Air shock broke a hospital window at the SW foot.

23 Jun 1984

--

Heavy ashfall caused a traffic jam and interrupted electric service in Kagoshima.

03 Jul 1984

--

Strong air shock broke windowpanes at a junior high school and a house in Koike at the W foot. A Sakura-jima Volcano Observatory employee was injured by broken glass in Yokoyama at the W foot.

07 Jul 1984

--

A large amount of lapilli broke 11 car windshields and a house windowpane at the NE foot.

21 Jul 1984

--

A large amount of ejecta including pieces up to a few meters in diameter fell at the S foot. Incandescent fragments broke the roofs of 10 houses and a warehouse, burning some slightly. Telephone and electric service was interrupted for a few hours.

Explosive activity at the summit crater of Minami-dake continued at a higher level, January-April (figure 10). The average monthly number of recorded explosions was 27, including larger ones that caused damage.

The number of recorded explosions at Sakura-jima in 1984 declined during July-November, but increased in December. Eruptive activity at the summit crater of Minami-dake caused damage around the volcano throughout the year.

Explosive activity at the summit crater of Minami-dake declined August-November, then increased in December when 59 explosions were recorded. An explosion at 1820 on 20 December was accompanied by an air shock powerful enough to have been recorded at Uwajima (260 km NE); ash and lapilli up to 2 cm in diameter fell on the road at the S foot and broke a car windshield. An explosion at 2132 on the 31st was accompanied by another strong air shock that broke 11 windowpanes in three of the hotels at the S foot. The rate of explosions decreased in January, when 20 were recorded. A strong air shock recorded at Uwajima, Nobeoka (140 km NE), Kumamoto (135 km N, and other places broke a windowpane in a S-foot hotel on 23 January.

An explosion at the summit crater of Minami-dake on 24 February at about 1030 ejected a plume to 4 km height. Lapilli 4-5 cm in diameter fell as far as 5 km SE of the crater, damaging 43 cars at the S foot and in Tarumizu City (5 km SE). Brush fires started by hot tephra quickly died. An air shock was recorded in Miyazaki, about 75 km to the NE. In the 4 hours after 1200, 140 swarm earthquakes were recorded.

Explosive activity at the summit crater of Minami-dake intensified in February, when 35 explosions were recorded (figure 11). The largest, at 1030 on the 24th, ejected a plume to an altitude of more than 4 km and was accompanied by a strong air shock that saturated the microbarograph at the Kagoshima Observatory. A strong NW wind carried a large amount of lapilli toward the SE foot. Between Arimura (3 km SSE) and Ushinefumoto (6 km ESE, in the middle of the city of Tarumizu), 28 car windshields were broken. Tile or slate roofs on 53 houses were slightly damaged at Ushinefumoto, and a windowpane was broken at Arimura. The number of recorded explosions increased to 54 in March, although the number expelling a large amount of ejecta decreased. Swarms of volcanic earthquakes were observed on 4, 17, and 19 February and 2, 8-9, and 24 March. On 31 March, an explosion sent lapilli 4-5 cm in diameter toward the SE foot, where 4 car windshields were cracked.

Activity remained at a high level in April, when 37 explosions were recorded, as compared to 35 in February and 54 in March. An explosion on 9 April at 1827 ejected a plume to 4 km above the crater, and was followed by 40 minutes of continuous ash emission and volcanic lightning. A small pyroclastic flow moved down the SW flank to about 600 m elevation. In the city of Kagoshima, ashfall began at 1840 and continued until around 0200 the next day. In the 24 hours beginning at 0900 on the 9th, ashfall at the Kagoshima Observatory was 1,608 g/m2, the largest daily total since measurements of ash deposits started in April 1969.

Another event of the same type occurred 13 April at 0722. The explosion earthquake was followed by continuous tremors, which gradually changed into a swarm of B-type earthquakes. Lapilli up to 1 cm in diameter fell on the foot, where four car windshields were cracked. On 3 May, Space Shuttle astronauts photographed a whitish, relatively diffuse plume that extended at least [50] km from Sakura-jima (figure 12).

Figure 12. Photograph of Sakura-jima taken by Space Shuttle astronauts on 3 May 1984 (STS51B-52-74). A plume extends more than 50 km NW. Courtesy of Charles A. Wood.

The number of recorded explosions increased from 10 in May to 33 in June and 60 in July. Explosions caused damage on 8, 13, 16, 22, and 30 June and on 6, 10, and 21 July. Bombs fell on roads and farms, producing large craters. A bomb from an explosion on 8 June at 1316 made a 1-m-diameter crater in a road near a residential area. On 13 June lapilli up to 3 cm in diameter fell on the S foot, cracking windshields and solar water heaters on rooftops. Ash fell heavily that day at Kagoshima and closed railway crossings. After an explosion on 16 June at 1147, a bomb fell on a farm, producing a crater 4 m in diameter and 0.8 m deep. On 22 June at 1029 an ash cloud rose 3.5 km. The air shock from the explosion broke windows at a school near the foot of the volcano, and falling lapilli cracked a car windshield on the E foot. Windshields of cars at the S foot were cracked by falling lapilli from a 30 June explosion. Total June ashfall was 1,510 g/m2 at JMA's Kagoshima Observatory.

Observations of the eruption column heights and quantity of ejecta were prevented by bad weather in early July. Debris flows from the volcano on 2 July blocked roads at three places after a heavy rainfall. On 6 July at 1720 a bomb fell on a house 3 km from the crater, briefly setting it afire and making a 2-m hole in the roof; no casualties or injuries occurred. On 10 July, incandescent rocks fell on an inhabited area in Arimura, at the S foot. One broke into pieces and cracked roof tiles on a house.

An airshock from a 21 July explosion broke windowpanes of a high school and a restaurant in the central part of Kagoshima. The explosion was followed by continuous emission of ash, which was carried toward Kagoshima. Early the next day, a Japan National Railway crossing gate in the N part of the city malfunctioned because of ash deposits on the rails; a car was struck by a train, but the car's driver was only slightly injured. Debris flows on 27 July blocked a road and broke buried water pipes at the S foot.

Ashfall was observed daily at the Kagoshima Observatory in late July. During the 24 hours beginning 28 July at 0900, ashfall was 2,476 g/m2, the largest daily total, raising monthly and yearly totals to the largest since measurements of ash deposits started in April 1969.

On 31 July, three explosions with large eruption columns at 0700, 0848, and 0951 were followed by vigorous ash emission that continued until about 1200. Driven by a SE wind, the ash fell over the W coast of Kyushu (figure 13).

Figure 13. Ashfall from 31 July 1985 explosions at Sakura-jima. Courtesy of JMA.

Explosive activity at the summit of Minami-dake declined in August, although vigorous ash emission was frequently observed. A large amount of ash fell on the city of Kagoshima, temporarily cutting off electric power and delaying trains. Lapilli broke car windshields and solar water heaters at 1919 on 11 August, at 0816 on the 14th, and at 1142 on the 16th.

Minami-dake's activity intensified in September, when 49 explosions were recorded. Successive vigorous ash emissions began with an explosion on 4 September at 1127, followed by three more the same day. An ash cloud moved N and slight ashfall was observed at many points in Kyushu and along the E coast of Honshu (figure 14, left). An eruption column on 9 September rose to 4 km above the summit. An explosion on 12 September at 0156 ejected lapilli up to 1 cm in diameter; a car windshield was broken at the SE foot. On 22 September, activity similar to that on the 4th sent ash over the E coast of Kyushu (figure 14, right).

Figure 14. Locations of reported ashfall from explosions of Sakura-jima on 4 September (left) and 22 September 1985 (right). Numbers beside data points on the 5-6 September map are ashfall in g/m2. Courtesy of JMA.

Forty-seven explosions were recorded in October, but there were no damages. Photographs by Space Shuttle astronauts on 3 and 4 October show a V-shaped plume to the SE of Sakura-jima.

Eruptive activity remained vigorous in November, when 34 explosions were recorded. Frequent powerful explosions produced air shocks and scattered incandescent blocks to about 2 km from the summit. No damages were reported. An explosion on 25 November at 1427 was accompanied by a small pyroclastic flow, which only covered part of the summit area.

The frequency of explosions increased further in early December. By the 5th, 19 explosions were recorded, bringing 1985's total to 416, the largest since discrete explosive activity began in 1955 (figure 15). A series of small explosions on 3 December shattered windows of several buildings in northern Kagoshima and disrupted telephone service in some areas. The summit crater of Minami-dake erupted on 5 December at 0220 and 0648, dropping ash on Kagoshima, but there was no damage.

Figure 15. Summary table of monthly and yearly number of explosions at Sakura-jima since the summit eruption began in 1955. Courtesy of JMA.

Weather satellite images on 24 and 31 December show eruption plumes from Sakura-jima. On the 24th an approximately 200-km plume extended SW, then turned E for about 60 km. The ash cloud was fairly dense and milky gray in color. On the 31st there was a 120-km V-shaped plume ESE of the volcano. The end of the plume was about 40 km wide and very diffuse.

Further Reference. Eto, T., Kamada, M., and Kobayashi, T., 1987, The 1983-1986 Activities of Sakura-jima Volcano in XIX IUGG General Assembly, 1987, Report on Volcanic Activities and Volcanological Studies in Japan for the Period from 1983 to 1986, p. 18-27.

"Frequency of explosions at the summit of Minami-dake further increased in December when a total of 75 explosions were recorded with at least one almost every day. A distinguishing characteristic of December volcanic activity was the reciprocal appearance of earthquake swarms and vigorous summit eruptions. Swarms of earthquakes were recorded on 1, 2, 3, 4, 8, 14, 17, 20, 21, 23, 26, 27, and 31 December, in almost every case the days of fewer explosions (except for 2, 3, and 30 December). Even on those 3 days, swarm activity occurred before or after the phase of summit explosive activity. This fact suggests that magma had been repeatedly and effectively transported in the conduit through the month.

"On 3 December at 0103, an explosion was accompanied by an airshock, strong enough to break 188 windowpanes in the city of Kagoshima, ~10 km W of the crater. Another strong shock on 19 December at 0546 broke 85 windowpanes and a car windshield in Ushine city, ~13 km ESE of the crater (table 7). In both cases, the presence of an inversion layer at 1,000 m altitude (3 December) and 1,500 m altitude (19 December) seemed to amplify the airshocks.

Table 7. Major episodes of damage to windows by airshocks, 1976-85. Damage from explosions at Sakura-jima, 1988-90. Car windshields were broken by block or lapilli fall, whereas windowpanes were mainly broken by air shocks. Ashfall damage is not included.

Date

Number of Airshocks

Location of Damage

17 May 1976

162

Tarumizu City, Furusato (3 km S)

01 Feb 1977

65

Tarumizu City

30 Nov 1977

102

Arimura (3 km SSE), Furusato (3 km S)

03 Dec 1985

188

Kagoshima City (10 km W), base of volcano

19 Dec 1985

85

Tarumizu City

"Lapilli also caused some damage: a windshield on a car was broken at Kurokami (4.5 km E of the crater) on the 5th, and at the volcano's SW foot on the 16th and 19th. An explosion on 19 December at 1810 ejected incandescent rocks and one of them made a 1-m-diameter hole near an inhabited house at Arimura (3 km SSE of the crater).

"In January, the monthly number of explosions declined to 35 and seismic activity also declined. Lapilli from an explosion on 1 January at 1158 broke the windshields of six cars at the SW foot.

"At [KLMO], 474 explosions were recorded in 1985 and cumulative ashfall was 15,908 g/m2, the largest since the summit eruptive activity began in 1955."

Eight explosions . . . were recorded in February and 13 in March. The explosions caused no damage. The maximum ash cloud height was 1,500 m above the crater. Bursts of microearthquakes, typical of Sakura-jima, occurred on 10, 11, 23, and 31 March.

In April, 55 explosions . . . were recorded. The highest ash cloud, on 25 April, rose 3,200 m above the crater. An air shock from an explosion on 16 April at 0537 broke windows and glass doors 3 km away at the foot of the volcano. Lapilli from an explosion on 23 April at 1207 broke car windshields near the volcano. Typical bursts of microearthquakes occurred on 5, 11, 15, 25, and 26 April.

Eight explosions were recorded in May . . ., a marked decline from April. The May explosions did not cause any damage. The month's highest ash cloud rose 1,000 m . . . on 21 May at 1014. Typical bursts of microearthquakes occurred on 3 and 16 May.

Twelve explosions . . . were recorded in June, increasing from eight in May. A total of 131 explosions were recorded January-June 1986.

Lapilli from an explosion on 10 June at 1100 broke windshields of three cars near the volcano; another windshield was broken on the 12th at 1024. Ash from the explosion on 12 June fell heavily at Kagoshima City (population 520,000), 10 km W of the volcano. Lapilli or blocks from the explosion on 24 June at 0912 broke windshields on eight cars and damaged roofs of about 30 houses near the volcano.

A TOA Domestic airlines DC9 with 152 passengers and a crew of six flew into the 24 June cloud at 1,200 m altitude, 23 minutes after it was ejected. Cockpit windshields and front surfaces of wings were badly scratched by ejecta. The airliner, enroute from Fukuoka, landed safely at Kagoshima. Damages to planes flying through volcanic clouds have occurred eight times near the volcano in the past (table 9).

Table 9. Damage to aircraft caused by tephra from Sakura-jima, 1970-June 1986. ANA: All Nippon Airways, TDA: Toa Domestic Airlines. Times are for explosions, rather than aircraft damage.

There were four recorded explosions . . . in July, on the 1st, 6th, 19th and 20th. Ashfall was heavy during the last part of the month, especially on the 28th and 30th. Some facilities of the National Railroad malfunctioned due to ashfall, causing delays in train operation on the 29th. Monthly ashfall accumulation was 1,533 g/m2, sixth highest since 1969 (when observation of ash accumulation started at KLMO). The maximum plume height over the crater was 3,000 m on 28 July.

Twenty explosions . . . were recorded in September. The maximum plume height was 1,800 m above the crater on 23 September. September ash accumulation at [KLMO] was 171 g/m2, an order of magnitude less than in June and July. Earthquake swarms occurred on 14 days in September.

At 1602 on 23 November, the 206th explosion recorded this year ejected a 2.5-m-diameter block onto a one-story concrete building at the foot of the volcano, 3 km S of the crater. Six people in the building were injured as the block, estimated to weigh 5 metric tons, broke through the roof and ground floor of the hotel and landed in the basement. Two other large blocks (1-1.5 m diameter) that landed near the hotel created a depression and started a grass fire. On 27 November, at 0532, 300-m eruption columns were emitted. Observers heard a loud explosion and saw blocks being ejected. Twelve explosions were recorded in November, and total ash accumulation was 52 g/m2, at [KLMO].

During October, 21 explosions were recorded and earthquake swarms occured on 9 days. The ash cloud reached its maximun height of 2,000 m above the crater on 11, 12, and 30 October. At 1150 on 30 October a large amount of lapilli was ejected, damaging three car windshields. A total of 25 g/m2 of ash accumulated at [KLMO].

Six explosions . . . were recorded during December, bringing the 1986 total to 213. Eruptive activity and seismicity increased toward the end of the month. Explosions on 19 December at 1347 and 30 December at 0916 ejected large amounts of lapilli that broke nearby car windshields. The 30 December ash cloud reached 2,500 m above the crater. Total ashfall for the month was 28 g/m2 at [KLMO]. Earthquake swarms occurred on 5 days.

During January, 13 explosions were recorded. Maximum ash cloud height was 2,800 m above Minami-dake crater, on 8 January. Earthquake swarms were recorded on 2, 4, 13, 18, and 20 January. No ash accumulation was recorded at [KLMO].

No explosions . . . were recorded in February or most of March but on 30 March at 2304 the 14th recorded explosion of 1987 occurred. Ash emissions without recorded explosion events had continued. The maximum ash cloud height was 1,300 m on 20 March. A total of 3 g/m2 of ash accumulated in March at [KLMO]. No ash had accumulated in February.

No explosions were recorded during April although ash clouds were often present. The maximum ash cloud height was 1,500 m above the summit crater (Minami-dake) on 3, 4, and 8 April. 43 g/m2 of ash accumulated at [KLMO]. Only one explosion has been recorded since 24 January. This is the lowest level of activity since May-August 1979.

An explosion was recorded . . . at 1718 on 14 May, for the first time in 1.5 months. Only two explosions had been recorded since 23 January but quiet ash emission occurred about 20 times a month during those four months. The explosion did not cause any damage. Three explosions were recorded in June, on the 14th, 15th, and 19th. Volcanic gas mixed with rain damaged the island's orange orchard and trees in Kagoshima City . . . on 15 and 16 June. Maximum ash cloud height was 1,500 m on 5 and 13 June. 335 g/m2 of ash accumulated in June at [KLMO]. About 100-400 explosions have been recorded yearly since 1955, with 476 explosions in 1985 and 216 in 1986. Only 18 explosions have been recorded this year, 13 in January.

Four explosions . . . were recorded in July . . . . Ash emissions without explosion shocks were often observed. The July explosions did not cause any damage. The maximum ash cloud height was 900 m above the crater on 25 July. A total of 81 g/m2 of ash accumulated in July at [KLMO]. Earthquake swarms were recorded on 16, 19, 20, and 25 July.

Three explosions . . . were recorded in August, bringing the 1987 total of explosions to 25. The month's highest ash plume reached 1,700 m and accompanied quiet ash emission on 22 August. Ash accumulated 51 g/m2 during the month at [KLMO]. The eruptions did not cause any damage.

Eighteen explosions . . . were recorded in September. Monthly ash accumulation at [KLMO] reached 1,093 g/m2, the largest value for September ash accumulation since measurement began in 1969. An explosion at 0612 on 24 September generated a loud sound and strong air shock. Lapilli broke or damaged seven car windshields, a house windowpane, 14 rooftop solar water heaters, and five roof tiles. A large amount of lapilli fell on the road from WNW to NW of the summit. The largest clast was 10-20 cm long. Ash emission following the explosion continued until 1330, resulting in heavy ash accumulation.

Sixteen explosions were recorded in October. No explosions had been recorded for about a month after a large explosion on 24 September, but the level of activity increased toward the end of October. Ash plumes rose to 3,000 m above the crater of Minami-dake on 29 and 31 October. Ten air shocks were felt and seven explosion sounds were heard during the month. October ash accumulation was 619 g/m2 at [KLMO].

Sixteen explosions from the summit crater, some causing damage, were recorded in November. The ash plume reached a maximum height of more than 4 km above the summit on 11 November. Monthly ash accumulation 10 km NW of the summit was 879 g/m2.

Three explosions were particularly strong. The first, at 1536 on 14 November, ejected a large amount of ash to 3.2 km height. Lapilli broke car windshields in the S part of the island. An explosion at 2056 on 17 November was the largest of 1987. An incandescent column reached 1 km, the highest since frequent explosions began in 1955. Large numbers of incandescent blocks were ejected for about 2 hours, burning cars parked at the foot of the volcano. More than 70 instances of volcanic lightning were observed in the eruption cloud. Eight car windshields and 23 solar water heaters were cracked by lapilli. A traffic accident, where a truck lost traction and crashed into a house, was attributed to volcanic ash that had fallen on the road. At 1119 on 28 November an explosion broke eight house windowpanes in Tarumizu city, 10 km SE of the summit. A window in a hotel on the S part of the island was cracked by the air shock.

Although the 1987 total of 106 explosions was significantly below the 216 recorded in 1986, December's 31 explosions represented the highest monthly figure of 1987, and an explosion on 19 December sent an ash plume to 3,500 m above the summit. Monthly ash accumulation at [KLMO] was 3 g/m2. Air shocks were felt at the observatory from 22 of the 31 explosions. No damage was reported.

January had 29 explosions, many of which ejected large amounts of lapilli. An explosion on 30 January at 2206 generated a loud sound, and a strong air shock that cracked 35 windowpanes at hotels and a house on the S part of the island. No explosion had damaged as many windows since 6 February 1986. January's highest ash plume reached 3,000 m above the crater at 1227 on the 3rd. Monthly ash accumulation at KLMO was 5 g/m2.

Explosive activity has become more vigorous in 1988. Explosions occurred at a rate of 1-2/day in February and often ejected large amounts of lapilli that fell on the flanks. The maximum ash cloud height was 2,500 m above the summit crater. A loud explosion at 1252 on 3 February ejected a large ash cloud, and strong air shocks were felt at [KLMO]. Lapilli broke the windshields of two cars and the air shock broke three windowpanes at a hotel and school. An explosion on 9 February at 1852 ejected a large amount of lapilli, breaking a car windshield. Ash accumulation at the observatory was 48 g/m2. February's 35 recorded explosions brought the year's total to 64.

The number of recorded explosions . . . declined from 35 in February to 21 in March . . . . The explosions often ejected large amounts of lapilli onto the flanks. At [KLMO], March ash accumulation totaled 934 g/m2; 15 explosion sounds were heard and 19 air shocks were felt there during the month.

An explosion on 27 March at 1252, accompanied by a loud sound and strong air shock, ejected an ash cloud that rose more than 4,000 m above the crater. Flank lapilli fall was heavy, breaking windshields of two cars at the E foot of the volcano, and the air shock cracked two windows at a hotel.

April's 19 recorded explosions brought the year's total to 104. No damage was reported. The maximum April ash cloud height was 2,000 m above Minami-dake crater, from the explosion at 0836 on the 20th. The month's ash accumulation was 222 g/m2 [at KLMO]. Air shocks were felt at the observatory from 18 of the 19 explosions.

Twelve explosions were recorded in May. Nine . . . were followed by air shocks. The month's highest plume rose 2,700 m after an explosion on 14 May at 0857. A total of 617 g/m2 of ash accumulated during May at [KLMO].

The number of recorded summit crater explosions declined to six in June, for a 6-month total of 122. A pair of explosions on 16 June deposited the largest amount of ash (2,671 g/m2) since measurements began in 1969 at KLMO . . . . The month's total ash accumulation was 3,541 g/m2. The largest previous ash accumulation at the observatory was 2,476 g/m2 on 29 July 1985. The 16 June plume was the month's highest (2.6 km). Four June explosions produced air shocks.

In July, 11 explosions . . . were recorded . . . . July's highest plume (3,300 m) was erupted at 1519 on the 9th. The monthly ash accumulation at the observatory was 59 g/m2, a sharp decrease from . . . June. The volcano was relatively quiet during the very successful International Conference on Volcanoes, sponsored by the Kagoshima Prefectural Government and held 19-23 July, just 10 km W of Sakura-jima's active vent.

In August, six explosions (four of which were followed by sounds) were recorded. Explosions on 4 and 5 August emitted the month's highest plumes (1,800 m). Ash ejections without recorded explosions were observed 13 and 29 August. A total of 175 g/m2 of ash accumulated 10 km W of the summit during the month. On the 24th, a swarm of B-type events was recorded by a seismometer 2.3 km NW of the summit.

In September, three explosions . . . were recorded. Two of the September explosions were followed by air shocks. Ash emission without explosion sounds occurred throughout the month. On 9 September at 0713, an explosion preceded emission of the month's highest plume (2,800 m). At the observatory, 523 g/m2 of ash accumulated during 13 days of ashfall in September. A total of 1,833 volcanic earthquakes were detected at the B station and earthquake swarms were recorded on five days (2, 3, 8, 9, and 29 September).

Activity was low during the first half of October but increased later in the month. Eight explosions were recorded, bringing the year's total to 150. Ashfall at [KLMO] dropped to 393 g/m2 in October. On 23 October, an ash plume reached 2,000 m altitude.

Satellite data showed a plume on 30 August that reached an estimated altitude of 3,600 m and extended ~110 km SE. On 27 September at 2329, a plume extended 40-50 km SE of the volcano, and on 13 October at 2137, a 3,000-m plume extended ~40 km ENE.

Explosive activity . . . continued with five explosions in November . . . . The explosions caused no damage. An explosion on 1 November at 0234 produced a large air shock and an incandescent column that was 500 m high for 10 seconds. Lightning was seen in the eruption cloud. The highest November ash cloud rose 1,000 m above the summit, accompanying an explosion at 1211 on the 10th. The month's ashfall at KLMO was only 12 g/m2.

A total of 155 explosions were recorded in 1988, compared to 106 in 1987. Yearly ash accumulation at [KLMO] was 6,503 g/m2, an increase from 1987. No explosions were recorded . . . during December, but two occurred in January, at 0944 on the 26th and 1758 on the 28th. The second event, accompanied by a loud explosive sound and strong air shock, ejected an ash plume to 2000 m above the crater. Windshields of eight cars on the S part of the island were broken by lapilli from the explosion. Only 4 g/m2 of ash accumulated at [KLMO] during [December]. A seismometer 2.3 km NW of the volcano registered 28,283 earthquakes in 1988.

In February, two explosions . . . were recorded, bringing the year's total to four. On 020 February at 0721, an explosion ejected a moderate amount of ash to 1,300 m. Another explosion at 1212 on 23 February produced a strong air shock and ejected blocks. During the month, 33 g/m2 of ash accumulated at the observatory.

In March, activity remained weak, with a small amount of ash emission on the 1st. Only one explosion . . . was recorded, bringing the year's total to five. The explosion, at 2258 on 11 March, ejected a 1,500-m plume and was accompanied by an air shock and small explosion sound. No damage was reported. Monthly ash accumulation at KLMO was 116 g/m2. An earthquake swarm was recorded 14-15 March by a seismometer 2.3 km NW of the crater.

Activity . . . in April was lower than in previous years. Single explosions were registered on the 1st, 5th, and 13th. The highest cloud rose 1,600 m on 13 April. Monthly ash accumulation at the observatory was 119 g/m2.

No explosions . . . were recorded in May or June, but plume emission continued. The highest plume in May rose 1800 m on the 19th. Ash accumulation in May was 112 g/m2 at the observatory. No earthquake swarms were recorded by the nearest seismometer, 2.3 km NW of the crater.

An explosion . . . on 31 August at 0401 was the 9th recorded in 1989. The explosion was accompanied by a strong air shock and a loud sound. A large amount of lapilli fell on the central flank, but caused no damage. No explosions had been recorded since 13 April, but plume emission had continued. August ash accumulation, 10 km west of the crater, was 1,198 g/m2.

Minami-dake summit crater frequently emitted small amounts of ash in September. The only two recorded explosions occurred at 0606 on the 5th and 1329 on the 17th. The latter ejected a 2,500-m ash plume, the highest of the month. The explosions caused no damage.

Ten explosions were recorded in October, raising the 1989 total to 21. The activity caused no damage. Maximum plume height was 2,200 m above the crater, on 14 October. The month's ash accumulation at KLMO . . . was 111 g/m2.

A total of 13 explosions were recorded in December; the largest, at 1155 on the 13th, ejected ash to 3,000 m above the crater. Monthly ash accumulation at [KLMO] was 13 g/m2. The explosions caused no damage.

A total of 44 explosions from the summit crater of Minami-dake were recorded in 1989, a decrease from 155 recorded in 1988. Yearly ash accumulation at KLMO was 2,352 g/m2. A seismometer (2.3 km NW of the crater) registered 18,296 earthquakes in 1989.

The summit crater of Minami-dake remained active, with 14 recorded explosions in both January and February. The largest, at 1003 on 11 January and 1659 on 24 February, ejected ash to 3,000 m above the crater rim, but did not cause any damage. Monthly ash accumulation [at KLMO] was 80 g/m2 in January and 144 g/m2 in February.

Explosions have been frequent since October 1989 . . . after 1 year of weaker activity. There were five recorded explosions in March, 12 in April, and 19 in May for a total of 64 in 1990. Ash clouds rose 1-3 km during larger explosions. An air shock from one explosion broke 21 windowpanes on the island and in the city of Kagoshima . . . . This was the first damage from explosions since January 1989. Monthly ash accumulations at the observatory were 457 g/m2 in March, 291 g/m2 in April, and 447 g/m2 in May.

The summit crater . . . remained active with 12 recorded explosions in June . . . . No damage was caused by the June explosions. An explosion at 1528 on 10 June ejected ash to 3,600 m above the crater, the highest cloud of the month. June ash accumulation [at KLMO] was 730 g/m2.

. . . Sixteen explosions were recorded in July, bringing the 1990 total to 92. No damage was caused by the July explosions. An explosion on 29 July produced a large ash cloud that rose 2,300 m and deposited 460 g/m2 of ash at [KLMO], the second largest daily amount this year. July ash accumulation was 781 g/m2.

During August, 20 explosions (with a maximum ash cloud height of 3,000 m on the 23rd) were recorded . . . . A monthly total of 2,307 g/m2 of ash was deposited 10 km W of the crater.

On 28 August at 0230, a large explosion ejected many blocks to the middle flank of the volcano. Twenty lightning flashes were seen in the volcanic cloud. Two car windshields were broken by lapilli 4 km from the summit and two blocks, roughly 60 cm across, fell 3 km S of the summit. No eruption-related damage had been reported since 1 May.

No explosions were recorded during September . . . . Quiet ash emissions occurred periodically, with a maximum column height of 1,800 m above the crater (on 11 and 28 September), producing significantly less ash than prior months . . . . An explosion was recorded on 4 October . . . .

Minami-dake cone exploded once in October, on the 4th, following 37 days of quiescence. No additional explosions had occurred as of 14 November. The October explosion was the 113th of 1990 and caused no damage. The maximum ash plume height, 3,500 m above the crater, occurred during a quiet emission on the 2nd. A monthly total of 130 g/m2 of ash was deposited 10 km W of the crater . . . .

Explosions . . . on 30 November at 0830 and 1504 . . . occurred after 57 days of quiescence. The ash plume from the morning explosion was the highest of the month, rising more than 4,000 m. Strong winds carried substantial quantities of ejecta southward. Lapilli/block fall 3 km S of the crater (at Arimura) broke four house windowpanes and 13 car windshields. Weather clouds obscured the plume from the afternoon explosion, but tephra was again blown southward by strong winds, breaking five more house windowpanes and seven car windshields at Arimura, and two car windshields at Tarumizu City, 8 km SE of the crater. The year's previous damage from Sakura-jima's explosions was on 1 May (windows broken by an air shock) and 28 August (two car windshields broken by lapilli). At total of 107 grams/m2 of ash were deposited [at the KLMO], down slightly from . . . October.

Minami-dake cone exploded four times in December, bringing the year's total of explosions to 119, up from 44 in 1989. An explosion at 0452 on 4 December ejected incandescent material that formed a column 500 m high, the highest since November 1988. Lightning was observed in the ash cloud for 26 minutes following the explosion. Another explosion, at 1019 on 25 December, ejected a 4,000-m-high ash cloud, and blocks that broke a car windshield 5 km E of the summit crater. It was the fifth event to cause damage during 1990 (table 10). The month's other two explosions occurred on 26 and 28 December. Only 4 g/m2 of ash was deposited 10 km W of the crater during December, a substantial decline from previous months.

Figure 16. Monthly number of recorded explosions at Sakura-jima, 1955-1990. Courtesy of JMA.

Table 10. Damage from explosions at Sakura-jima, 1988-1990. Car windshields were broken by block or lapilli-fall, whereas windowpanes were mainly broken by air shocks. Ashfall damage is not included. Courtesy of JMSA.

Date

Damage

30 Jan 1988

35 house windowpanes.

03 Feb 1988

Two car windowshields and four windowpanes.

09 Feb 1988

One car windshield.

27 Mar 1988

Two car windshields.

28 Jan 1989

Eight car windshields.

01 May 1990

21 house windowpanes.

28 Aug 1990

Two car windshields.

30 Nov 1990

Thirteen car windshields and four windowpanes.

30 Nov 1990

Nine car windshields and five windowpanes.

25 Dec 1990

One car windshield.

Further References. Eto, T., 1988, An estimation of the amount and dispersal of volcanic ash-falls ejected by summit eruptions at Sakura-jima volcano: Proceedings, Kagoshima International Conference on Volcanoes, p. 448-451.

Minami-dake cone had ten recorded explosions in February, but the activity caused no damage. The month's highest ash cloud reached 1,200 m. A total of 6 grams/m2 of ash was deposited [at KLMO]. Two swarms of volcanic earthquakes were recorded, on 16 and 28 February.

Minami-dake cone exploded 37 times in March . . ., the highest monthly total since February 1988. No damages were caused by the explosions. The month's highest ash cloud reached 2,700 m. A total of 19 g/m2 of ash was deposited in March [at KLMO]. Swarms of volcanic earthquakes were recorded on 6, 8, 12, and 20 March.

Explosive activity has remained at high levels since mid-January, totaling . . . 42 [explosions] in April (the highest monthly total since April 1986), and 15 through 16 May . . . . The explosions caused no damage. The highest April ash cloud rose 3,000 m on the 30th. April ashfall was 187 g/m2 [at KLMO]. Earthquake swarms were recorded on four days, a normal monthly total for the volcano.

Frequent explosions continued through mid-June, with 17 recorded in May and 20 as of 19 June, bringing the year's total to 142. The highest ash clouds rose 3,000 m on 3 May and 2300 m on 18 June. An air shock from a 10 May explosion broke a window, the first explosion damage since December 1990.

Frequent explosive activity . . . continued through mid-July. Explosions . . . occurred 31 times in June . . . and 15 times by 24 July, bringing the year's total to 168. An explosion at 2345 on 29 June ejected blocks and lapilli that damaged house roofs and two car windshields, the second episode of explosion-related damage in 1991. The ash cloud rose to a maximum height of 3,200 m (on 27 June), and a monthly total of 20 g/m2 of ash was deposited 10 km W of the crater (compared to 209 g/m2 in May). Volcanic earthquake swarms, similar to previous months, were recorded on 7, 16, 24, and 28 June.

Eighteen explosions occurred . . . in July . . ., bringing the yearly total to 171. Ejecta from an explosion at 1057 on 5 August struck the windshield of a Boeing 737 airliner 13 minutes later as it flew at an altitude of 1.2 km, 10 km N of the volcano. A crack 50 cm long formed in the outer surface of the windshield, but the plane (domestic flight ANK 793) landed its 122 passengers and five crew safely. Dense weather clouds had prevented the pilot from seeing the eruption plume. This was the first incident of in-flight damage since 24 June 1986, and the 12th near the volcano since 1975. A car windshield a few kilometers from the crater was cracked by ejecta from another explosion (at 1249) the same day. These were the third and fourth cases of explosion-related damage in 1991.

Nineteen explosions occurred . . . in August . . . . Ejecta from an explosion on 5 August at 1057 cracked the windshield of an airliner in flight. A car windshield was cracked by tephra from an explosion at 1249 the same day and another was broken on 20 August at 0851, both on Sakura-jima Island, 3 km from the crater. The month's highest ash cloud rose 4,000 m. A total of 583 g/m2 of ash was deposited [at KLMO]; a change in the usual wind direction had carried ash away from this site in July. Typical volcanic earthquake swarms were recorded on 3, 15, 16, and 29 August.

Similar activity continued through mid-September, adding 15 explosions as of the 14th . . . . The highest September ash cloud reached 1,800 m height.

The 32 recorded explosions . . . in October . . . caused no damage. The month's highest ash cloud rose 4 km above the crater. Ash deposition [at KLMO] was 93 g/m2 . . . . Swarms of volcanic earthquakes were recorded on 2, 4, 10, and 18 October. Explosions became less frequent in November, with only three as of the 17th . . . .

Fifteen explosions were recorded in November . . . . A car windshield was cracked by lapilli from the month's highest ash cloud (3,000 m), emitted at 1245 on 18 November. A total of 332 g/m2 of ash was deposited [at KLMO] in November . . . . Swarms of volcanic earthquakes were recorded on 3, 5, 10, 19, and 28 November.

The number of explosions . . . increased . . . to 37 in December (figure 17), bringing the 1991 total to 295, the highest since 474 explosions were recorded in 1985. The December 1991 activity deposited 266 g/m2 of ash [at KLMO] . . . . An explosion at 1742 on 16 December produced the month's highest ash cloud, which rose more than 3 km above the crater. The air shock from an explosion on 5 December at 1246 broke a glass door; no other damage was reported. Similar eruptive activity continued through mid-January, adding 15 explosions by the 17th. Seismicity was more vigorous than usual during December. Swarms of volcanic earthquakes were recorded on 1, 3, 16, 17, 21-27, and 29 December.

Figure 17. Monthly number of explosions (top) and ash accumulation 10 km W of the crater (bottom) at Sakura-jima, 1980-1991. Courtesy of JMA.

Sixty explosions were recorded at Minami-dake cone in January, . . . marking the highest monthly total since December 1985. The month's highest ash cloud rose > 2,500 m at 0906 on 16 January, and a car windshield was cracked by lapilli during an explosion at 1725 on 2 January. A total of 206 g/m2 of ash was deposited [at KLMO] during the month . . . . Seismicity was higher than usual, with earthquake swarms on 5, 7, 9, 10, 15, 19, 20, and 26 January. Similar activity continued through early February.

The monthly number of recorded explosions declined from a 6-year high of 60 in January, to 16 in February. Seven car wind shields were cracked by lapilli from an explosion at 1009 on 1 February, and two more were cracked at 0630 on 2 February, when the month's highest plume rose 3.5 km. Seismicity was higher than normal, with swarms of volcanic earthquakes recorded on 4, 7-15, 17-19, and 23-29 February.

Ten explosions were recorded . . . in March . . . . The month's highest ash cloud rose 1,900 m on 13 March. Seismicity was more vigorous than usual, with volcanic earthquake swarms recorded almost daily from 14 to 29 March, each lasting 4-5 hours.

Only two explosions occurred . . . in June, causing no damage. The month's highest ash clouds rose 2,000 m on 9 and 18 June. Two 9-hour swarms of volcanic earthquakes were recorded, a relatively low level of seismicity for the volcano.

Six explosions . . . occurred in July, but caused no damage. Although explosions detected by seismic instruments, sounds, and air shocks have been infrequent since May, 31 quiet ash emissions were seen in May, 14 in June, and 19 in July, comparable to previous months. Ground observers reported that July's highest ash cloud rose 3.5 km (to ~4.5 km altitude) on the 29th. Captain Greg Wolfsheimer (Northwest Airlines) reported that a moderately dense, light-gray cloud was rising to more than 5 km altitude when his aircraft passed Sakura-jima at 1735 that day. No volcanic earthquake swarms were recorded in July.

No explosions were recorded in August, the first explosion-free month since September 1990. However, ash eruptions without explosion shocks were seen nine times in August. Ash plumes rose 3.5 km . . . on 15 August and 3.2 km on 21 August. The KLMO . . . counts explosions detected by seismometer, microbarometer, felt air-shocks, and sounds. Quiet ash eruptions are detected visually. No swarms of volcanic earthquakes were reported during August.

Similar activity continued through 15 September, with three recorded explosions and seven quiet eruptions. On 7 September at 0552, the first explosion since 29 July ejected a 3-km ash plume with electrical discharges. Ash rose 3.5 km in a quiet eruption on 4 September.

An explosion occurred . . . on 7 September, the first since 29 July. Another five explosions were detected and eight quiet ash eruptions were observed in September. The highest ash plume rose 3.5 km . . . on 4 September. No damage has been caused by these eruptions.

Eighteen explosions and 18 ash eruptions occurred . . . in October, a significant increase from September. Ten of the 18 seismically recorded explosions produced an incandescent column. The highest column rose 800 m for 60 seconds at 0440 on 20 October, scattering incandescent blocks to 700 m distance. This was the first large incandescent column since glowing material rose 1,000 m on 13 July 1991. The month's highest ash plume rose more than 4 km . . . at 0843 on 22 October. Seismicity was relatively low with no swarms recorded.

Activity continued at a similar rate, with nine explosions and four quiet ash eruptions, through mid-November. The highest ash plume rose 3 km on 11 November. Explosions on 8 and 13 November produced incandescent columns, each lasting 10 seconds and rising 200-300 m.

Twelve explosions and three quiet ash eruptions occurred . . . in December . . . . No damage was caused by the eruptions. The highest ash plume rose 2 km on 22 December. Seismicity remained relatively low, with one swarm of 29 earthquakes on 29 December between 0700 and 1900.

A total of 165 explosions was recorded in 1992, down from 295 last year. Yearly ash accumulation [at KLMO] was 2,945 g/m2, up from 1,852 g/m2 in 1991.

Sixteen explosions occurred . . . in January . . . . No damage was caused by the explosions. The highest ash plume rose 2,900 m on 22 January at 1109. Seismicity remained normal, with two swarms of B-type earthquakes on January 23 (duration 6 hours) and 25 (3 hours).

Explosions . . . continued at a rate similar to that recorded in January. Two of the 15 explosions recorded in February produced observable incandescent columns rising 100 m above the crater. An explosion at 1822 on 3 February produced the highest ash plume of the month, 2,000 m. Seismicity remained normal. Three swarms of B-type earthquakes were recorded: on 9 February (duration 5 hours), 10 February (5 hours), and 25 February (10 hours).

Seven explosions . . . were recorded in April . . . . Lapilli from an explosion at 1425 on 7 April cracked the windshield of an automobile on the volcano's island. It was the first direct damage from an explosion since February when windshields from nine autos were damaged. An explosion at 0948 on 2 April produced the highest ash plume of the month, >3,200 m above the crater. No earthquake swarms were recorded.

No explosions occurred . . . in May . . . . The interval 8 April through 14 June (68 days), is the longest explosion-free period since 1989, when 139 consecutive days (between April and August) were without explosions. There were, however, explosion-free ash eruptions during this interval. The first quiet ash eruption was on 24 May, and other single eruptions were recorded on 24, 27, 28, and 30 May, and 12-14 June. The highest ash column of the month rose 2,500 m above the summit on 24 May, and a 3,000-m column was observed 1 June. Seismicity was also at low levels in May and early June.

A total of 13 non-explosive ash eruptions occurred . . . in June . . . . Explosive eruptions accompanying seismic and atmospheric shocks have not occurred between 8 April and 16 July (99 days). This is the longest explosion-free period since 1989, when 139 consecutive days (between April and August) were without explosions. The highest ash cloud of the month, on 1 June, rose 3,000 m above the summit. No earthquake swarms were recorded in June.

July was the first eruption-free month since June 1989, although a white (occasionally gray) plume weakly rose 100-200 m above the crater rim throughout the month. Seismicity in July was about 10% of normal, with 331 small earthquakes recorded. . . . Eruptive activity had not resumed as of 13 September, bringing the sequence of explosion-free days to 159 since 8 April. This is the longest explosion-free period in over 20 years. Since the current eruption began in 1955, the longest quiet period prior to this was 307 days from April 1971 until March 1972.

During September, a white plume weakly rose ~200 m above the crater, similar to the plume observed in July and August. A small amount of ash was contained in the steam plume in late September. Seismicity and volcanic activity remained low through mid-October. Volcanic activity resumed on 20 October when non-explosive eruptions ejected ash 2.1 km above the crater.

An explosive eruption on 26 October ended the sequence of 201 explosion-free days, the second longest quiet period since the current eruption began in 1955. The longest such period lasted for 307 days, from April 1971 until March 1972. Eight more explosions had occurred by 13 November, bringing the total number of explosions in 1993 to 65. The last explosion, on 10 November, ejected ash up to 1.4 km. No damage was caused by any of the eruptions. Earthquake swarms on 5 and 9 November lasted 8 and 13 hours, respectively.

. . . after 26 October more explosions took place. In late October there were three explosions, and in November there were 10. Explosions continued at similar levels through early December . . . . No damage was caused by the explosions. The highest ash plume of the month rose 2,300 m above the crater on 27 November. Volcanic earthquake swarms on 5 and 9 November lasted 8 and 13 hours, respectively.

Explosive volcanism continued during December, with 21 explosions recorded, bringing the total number of explosions in 1993 to 91. The highest ash plume of the month rose to 3.5 km on the afternoon of 9 December. Explosive activity has shown a slightly increasing trend since it resumed on 26 October 1993 . . . .

Explosive activity decreased with only five explosions in January . . .; no damage was caused. The highest ash plume of the month rose to 3,000 m in the late morning hours of 27 January. There were no volcanic earthquake swarms recorded in January.

Explosive volcanism continued in February with 11 distinct eruptions. Ejecta from an explosion on 2 February cracked a car windshield and generated an ash plume that rose 2.5 km, the highest of the month. No volcanic earthquake swarms were registered in February.

During the interval 20 February-2 April no eruptions occurred. One minor eruption did take place at 1530 on 3 April, when the volcano sent an ash plume to 1.4 km height. After that Sakura-jima exhibited a low level of activity (no earthquake swarms) through early May. . . .

Volcanic activity has remained low since the last explosive eruption on 20 February. However, a non-explosive eruption generated an ash plume to 1,400 m altitude on 3 April (19:04). The highest ash plume of the month rose to 1,800 m above sea
level at 1506 on 1 May . . . . Two explosions on 30 May caused no damage. Explosive activity has increased since then, with frequent explosions in June.

No damage was caused by any of the 31 eruptions that occurred in June, 19 of which were explosive. Frequent explosions continued through early July. The highest ash plume rose to 2,600 m at 1624 on 7 June. Volcanic earthquake swarms were detected between 1400 and 2200 on 27 June, and during 1600-2200 on the 29th; maximum amplitude was 1.0 µm. [KLMO] measured 31 g/m3 of ashfall during the month.

The following report is from Steve O'Meara. Around 1700 on 29 May the volcano was heavily emitting steam with sand-colored ash. By 1719 part of the steam cloud contained gray ash, giving the appearance of "zebra stripes" in the column. A strong gray cloud was being erupted by 1803 and being blown E by the wind. At 0500 on 30 May, very little steam was evident, however, by 0850 the steam was thicker, and by 1022 an ash eruption was producing gritty ashfall halfway across the bay from Kagoshima city. From the Unohira lookout station W of the volcano, observers noted large ash plumes being released every few seconds. No eruption sounds were detected until 1127 when a low-pitched banging noise could be heard. Ash was accumulating rapidly at the station; by 1135 the ash cloud was filling the intervening valley. Additional observations from the SE and S later that afternoon included steam and steam-and-ash emissions with roaring, rumbling, or jetting sounds. A heavier eruption began in pulses at 1530-1600, with large, sustained ash clouds released about every 5 minutes. A large ash cloud remained at least through 2200, and the eruption was over by 1150 the next day (31 May). Another eruption began at 1630 on 31 May. It sent ash plumes towards Kagoshima and was accompanied by sounds like muted cannon fire.

Sakura-jima generated 22 eruptions in July, including 14 explosive ones. None of them caused damage. The highest plume rose to 2.2 km (at 1859 on 5 July). In July, the amount of ashfall at [KLMO] was 237 g/m3. Volcanic swarms were absent in July but 520 earthquakes were detected at a seismic station 2.3 km NW of Minami-dake crater.

Volcanic activity increased in August . . . with 55 eruptions . . . including 17 explosive ones. No damage was caused. The highest ash plume of the month rose to 3,200 m at 1725 on 24 August. No volcanic swarms were registered, but 861 earthquakes were detected at a station 2.3 km NW of Minamidake crater. Heavy ashfall was observed on 21 August (159 g/m2) at [KLMO]. Total ashfall . . . during August was 425 g/m2.

Explosive volcanism continued through September but caused no damage. Nine eruptions occurred . . ., including four explosive ones, a significant decrease from last month. The highest ash plume of September rose to 3,200 m on the morning of 12 September. No volcanic earthquake swarms were detected, but 438 distinct events were registered at a seismic station 2.3 km NW of Minami-dake crater. Ashfall was sometimes observed at [KLMO], where 425 g/m2 was measured in September.

Explosive volcanism continued through October but caused no damage. There were 31 eruptions . . ., including 14 explosive ones. On 5 October a NOTAM . . . described eruptions at 0136 and 0447 that rose to 3.35 km. On the other hand, JMA reported that at 1628 on 6 October the "highest ash plume of October" rose to 3.3 km, so apparently there was relatively vigorous activity on both days. Volcanic earthquake swarms were detected 130 times, reaching a maximum amplitude of 2 µm. During October, a seismic station 2.3 km NW of Minamidake crater registered 862 distinct events. October ashfall collected at the Kagoshima Meteorological Station, 10 km W, measured 136 g/m2.

Explosive volcanism continued through November 1994; it caused no damage and was lower than last month in both the number of eruptions and the mass of ash fall collected. There were 21 eruptions from Minami-dake crater, including eight explosive ones. The highest ash plume in November rose to 2,700 m (at 1435 on 10 November). Seismic swarms were registered at a seismic station 2.3 km NW of Minamidake cone between 1900 on 30 November and 0700 on 1 December; earthquakes for the month numbered 427. During November, the mass of ash fall collected [at KLMO], was 60 g/m2.

Volcano monitoring at Kagoshima airport. Recent papers discussed the challenge of operating aircraft in vicinity of active volcanoes, including Sakura-jima (Onodera and Kamo, 1994; Casadevall, 1994). In Japan, 19 out of 83 volcanoes are actively steaming and under constant surveillance by JMA headquarters or local observatories; the other volcanoes are regularly patrolled by "Mobile Volcanic Observation Teams" based in four cities. These surveillance groups disseminate critical eruption information to relevant organizations, for example, Aviation Weather Service Centers, Air Traffic Control Centers, and airlines.

The key components of the Sakura-jima monitoring system consist of a seismometer for detecting earthquakes and an infrasonic microphone for detecting air shocks produced by explosive eruptions. An additional prediction system includes other instruments, such as water tube tiltmeters and extensometers. Even though the monitoring system can detect volcanic emissions nearly instantaneously, a time delay of at least a couple of minutes allows volcanological officers to confirm the responses of the monitoring equipment. This time delay also allows for time to edit and dispatch outgoing SIGMET or notification messages. In general, a SIGMET (Significant Meteorological Event) gets issued when the volcanic ash cloud reaches cruising flight elevation or higher.

While in general the several-minute time delay may not cause serious aviation safety problems, it may be crucial when aircraft are close to volcanoes, as at Sakura-jima. In considering problems such as these, the investigators developed a working model to quantify hazards. They expressed the relationship between magnitude of danger (D), eruption magnitude (M), volcano-aircraft distance (L), and a constant that may be affected by wind and related atmospheric conditions (k): D = kM/L.

Aircraft operations adjacent Sakura-jima. Figure 18 shows Kagoshima airport, at the S tip of Kyushu Island, sitting 22 km N of Sakura-jima's active crater. One of Japan's busiest airports, it has about 130 large transport takeoffs and landings a day; aircraft on the lowest category approach (ILS RWY34) pass a point 17 km NE of Sakura-jima's crater. Meanwhile, Sakura-jima produces over 100 explosive eruptions a year on average, but over 400 eruptions on some years (figure 19). Ash production has also been measured for the years 1978-93 (figure 20). It varied by a factor of about 5.5. At Sakura-jima there were 12 encounters between aircraft and volcanic ash during the years 1975-91 (Onodera and Kamo, 1994).

Figure 18. Sakura-jima airport showing both normal and ash avoidance air routes (top). More detailed map of the volcano and airport showing an air route and the JAL observation site (bottom). Courtesy of Onadera, Iguchi, and Ishihara.

Figure 19. Annual number of explosions and mass of ashfall from Sakura-jima (1978-1993, with 1994 annual total up to July also shown). Courtesy of Onadera, Iguchi, and Ishihara.

Figure 20. Annual number of explosions from Sakura-jima (1955 to July 1994). Arrows indicate small pyroclastic-flow episodes. Courtesy of Onadera and others (1994).

Explosive volcanism . . . continued during December with 64 eruptions, including 54 explosions; no damage occurred. The highest ash plume of the month rose > 2.5 km on 30 December. Volcanic swarms registered at a seismic station 2.3 km NW of Minamidake on 18-19 and 23 December. A total of 743 earthquakes were registered during the month. The ashfall measured at [KLMO] was 16 g/m3.

Volcanism at Sakura-jima in 1994 was generally moderate, with explosive activity during January-February and June-December. Explosions on 2 February broke windshields of two cars. The total number of eruptions in 1994 was 277, including 148 explosive ones.

Activity from Minami-dake crater continued in January with 47 eruptive events, including 41 explosions; no damage was caused. Explosion sounds were heard during nine of these events by personnel at the Kagoshima Meteorological Observatory (10 km W). The highest ash plume of the month rose 2.5 km on 26 January. The next day, a "fire column" rose 300 m above the crater rim. Rockfalls on the 31st travelled midway down the slope of the volcano. A total of 715 volcanic earthquakes registered at the station 2.3 km NW of Minami-dake crater during January. The monthly ashfall amount (10 km W of the crater) was 15 g/m2.

Explosive volcanism continued in February and March from Minami-dake crater but caused no damage. There were a total of 22 eruptions in February, including 12 explosive ones. Activity increased somewhat in March with 36 eruptions, 24 of which were explosive. The highest monthly ash plumes occurred on 11 February (3 km) and on 8 March (4 km). Ashfall measured 10 km W at the Kagoshima Meteorological Observatory (KMO) was 30 g/m2 in February. Although there were more eruptions, only 9 g/m2 of ash fell at KMO during March.

An earthquake swarm that started at 1600 on 23 February lasted 9 hours and consisted of 99 events registered at Station B, 2.3 km NE of Minami-dake crater. This episode caused the KMO to issue a Volcanic Advisory noting the restlessness of the volcano. Station B also registered 208.8 hours of volcanic tremor and a total of 424 volcanic earthquakes during February. Another earthquake swarm between 0000 on 26 March and 0300 on 28 March produced 2,041 earthquakes and 828 tremors, causing another two Volcanic Advisories. However, total amount of tremor in March (164.3 hours) was less than in February.

During April and May, explosive volcanism continued from Minami-dake crater. Throughout April there were 16 eruptions, 13 of them explosive, with the highest ash plume rising 1,800 m above the summit crater on 7 April (table 11). In May there were 36 eruptions, 17 of which were explosive. The highest ash plume of May rose 2,500 m on the 23rd. Monthly ashfall amounts, collected at Kagoshima Meteorological Observatory, 10 km W of Minami-dake crater, were 14 g/m2 and 20 g/m2, respectively for April and May.

At a seismic station 2.3 km NE of Minami-dake crater (Station B), 887 earthquakes were recorded in April, and 1,008 in May. Between 1100 and 2200 on 1 April, 147 volcanic earthquakes were registered. There were 427 tremors with a total duration of 138 hours during April, and 815 tremors in May lasted a total of 72 hours.

Volcanism at Sakura-jima continued at a moderate rate through June, and dwindled in July. Throughout June there were 18 eruptions, 10 which were explosive. The highest ash plume of June reached 2,500 m elevation (2 June). The monthly ashfall accumulation at Kagoshima Meteorological Observatory, 10 km W of Minami-dake crater, was 11 g/m2. Throughout June, 550 earthquakes and 349 tremors were recorded at Station B, 2.3 km NE of Minami-dake crater.

During July, Sakura-jima generated only one explosive eruption. The 18 July ash plume rose 2,100 m above the crater rim. The monthly ash fall accumulated at Kagoshima Observatory measured 5g/m2. An earthquake swarm consisting of ~170 events occurred during 1600-2100 on 31 July. The totals for the numbers of monthly earthquakes and tremors at Station B were 655 and 533, respectively.

During 1995, the geophysical system described below registered Sakura-jima's 126th explosion on 23 August. During 23-25 August, 28 explosions were recorded. The total through August of 153 explosions is relatively small compared to 1960, 1974, 1983, and 1985, years when over 400 explosions took place. During August no measurable ash fell at Kagoshima Local Meteorological Observatory, 10 km W of the crater. On the other hand, ash-bearing explosions were of sufficient size to send a dense ash cloud NW of the volcano that dropped ash in N Kyushu and closed a highway for an unspecified duration. The highest plume of the month vented on 30 August and rose to 3 km above the crater rim. Station B (2.3 km NE of Minami-dake crater) registered 671 earthquakes and 378 tremor events.

Geophysical determination of explosions. The monthly tally of "explosions" (sometimes also called "explosive eruptions") at Sakura-jima has a geophysical definition, with its origins closely linked to aircraft safety. The volcano sits ~25 km from the busy Kagoshima International Airport and generates frequent Vulcanian explosive eruptions (BGVN 19:11). A video camera monitors the volcano and a real-time image is transmitted to air traffic control. In order to alert aviation dispatchers and pilots of potential hazards regardless of the time of day or the weather, scientists devised a system to rapidly classify the volcano's seismic and acoustic signals (Onodera and Kamo, 1994). This geophysical system has been linked to the Japan Airlines office at Kagoshima Airport since March 1991.

When the amplitudes of incoming seismic signals rise above an established threshold (table 12) their dominant frequency is computed. The above-threshold signals also have an associated air-shock wave that is received at an "infrasonic" microphone with a 0.02-100 Hz detection range. For reference, the low-frequency range of the human ear stops at around 16 Hz. Once the infrasonic air-shock wave is received, the system measures its amplitude and computes its spectrum. The combination of seismic and air-shock amplitudes and spectra allow the events to be classified into "non-eruption," "eruption," or "explosion." categories (table 2).

Accompanied by strong air-shock waves, and bomb- and ash-bearing. Maximum amplitudes range from 3 x 10-3 to 3 x 10-2 cm/s for the earthquakes (reduced displacements of 50-500 cm2) and 0.1 to 5 mb for the infrasonic air-shock waves.

Although passing typhoons can trigger inappropriate warnings or false alarms, and small-magnitude eruptions may be missed, the number of explosions correlates well with the measured deposition of fresh volcanic ash. The system has been effective at reducing aviation risks. A future goal is to use "explosion" category to automatically trigger the calculation of volcanic ash diffusion based on meteorological data. This program would thus automatically estimate the likely trajectory of ash discharged from the volcano.

Activity at Minami-dake crater became high during both early and late October. On 28 October, 9 explosive eruptions occurred and significant volcanic ash fell in Kagoshima City. During October, seismic station B (2.3 km NE of Minami-dake crater) recorded 720 earthquakes and 1,206 tremors. On 27-28 October there were seismic swarms. During October the volcano produced 31 eruptions, 23 of them explosive; the highest ash plume, on 28 October, rose 3 km above the summit crater. October ashfall (measured 10 km W at the Kagoshima Meteorological Observatory) was 117 g/m2.

Minami-dake crater was active throughout November-December 1995. Eruption totals for November and December were 19 and 42, respectively. Of these, explosive eruptions for the same months numbered 14 and 36, respectively. The local seismic station recorded 453 earthquakes and 446 tremors during November and 467 earthquakes and 83 tremors during December. The highest monthly ash plumes took place on 30 November (2,300 m above the crater), and on 9 December (1,700 m). Ashfall measured 10 km W of the crater was as follows: November, 5 g/m2; and December, 18 g/m2.

Minami-dake crater was slightly active throughout January. The monthly total number of eruptions was 60, including 42 explosive ones. At the seismic station 2.3 km NW of Minami-dake crater (Station B), 601 earthquakes and 684 tremors were recorded. The highest ash plume of the month rose 2,300 m above the summit crater on the 21st. Ashfall measured at the Kagoshima Local Meteorological Observatory, 10 km W form the crater, was 41 g/m2.

The VRC noted that there were more than 200 eruptions in 1995; total amount of erupted material was estimated at 3-4 million tons by the Sakurajima Volcanological Observatory, Kyoto University. The latter has been observing continuous uplift on the N side of the volcano, implying accumulation of magma beneath the volcano.

During February Minami-dake Crater produced 35 eruptions, including 31 that were explosive. At the seismic station 2.3 km NW of Minami-dake Crater (Station B), 689 earthquakes and 879 tremors were recorded. On 11 February, the highest ash plume during the month rose 1,800 m above the summit crater. Ashfall measured at the Kagoshima Local Meteorological Observatory (KMO), 10 km W of the crater, was 10 g/m2.

Minor activity continued at Minami-dake until mid-March, although the highest ash plume of the month rose 2,100 m above the crater on the 6th. Twelve explosive eruptions occurred on 18 March. Overall during March there were 88 eruptions, 69 of which were explosive. The monthly total ashfall measured 10 km W of the crater was 22 g/m2. Seismicity recorded 2.3 km NW of the crater during March consisted of 970 earthquakes and 773 tremors.

During April, Miniami-dake crater produced 14 eruptions, including five that were explosive. Seismic station B, 2.3 km NW of Miniami-dake crater, recorded 364 earthquakes and 120 tremors. On 28 April an ash plume rose 3,500 m above the summit crater. This was the highest ash plume observed during the month. A monthly ashfall total of 8 g/m2 of ashfall was measured at the Kagoshima Local Meteorological Observatory (KMO), 10 km W from the crater.

During May, Minami-dake crater produced one explosive eruption. Station B recorded 64 earthquakes and three tremors. The highest ash plume of May rose 3,500 m above the summit crater. The ashfall total at KMO was 6 g/m2.

An eruption on 16 May sent an ash plume 3,500 m above the summit, to ~4,600 m altitude (BGVN 21:05). This higher than usual ash plume was estimated at 4,880 m altitude in aviation notices from Tokyo. However, the eruption was not detected on GMS satellite imagery. Ths Volcano Research Center also noted that this explosion threw large cinders to 2 km NW of the crater.

According to the Sakura-jima Volcanological Observatory (SVO), Kyoto University, since March there has been a decrease in the amount of air-fall tephra, the frequency of explosions, and earthquakes (including BL, surface, and shallow types).

The Japanese Meterological Agency reported that Minami-dake crater produced four explosive eruptions during June. The highest ash plume of the month rose 900 m above the crater on 22 June. Ashfall measured at the Kagoshima Local Meteorological Station, 10 km from the crater, was 1 g/m2. The seismic station 2.3 km NW of the crater recorded 118 earthquakes and 63 tremors through 29 June. High seismicity began around 0800 on 30 June; 349 earthquakes were recorded that day, bringing the monthly total to 467.

Minami-dake crater had one non-explosive eruption in July. The seismic station 2.3 km NW of the crater (Station B) recorded 136 earthquakes and 29 tremors during July. No ashfall was found at the Kagoshima Local Meteorological Observatory, 10 km W of the crater.

During September, five explosive eruptions occurred in Minami-dake crater, producing 3 g/m2 of ashfall measured at the Kagoshima Local Meteorological Observatory (KMO), 10 km W of the crater. Totals of 145 earthquakes and 43 tremors were recorded during September at Station B, 2.3 km NW of Minami-dake crater. In contrast, eruptive and seismic activity decreased in October. During October, there were two explosive eruptions in Minami-dake crater with <1 g/m2 ashfall at KMO; 19 earthquakes and one tremor were registered at Station B. The highest plume in October rose 1,300 m above the summit crater.

During December and January, Minami-dake crater had six eruptions (four explosive). At a seismic station 2.3 km NW of Minami-dake crater, 342 earthquakes and 14 tremors were recorded in December, and 257 earthquakes and 18 tremors were recorded in January. The highest plume in December rose to a height of 2,700 m. The monthly ashfall measured at the Kagoshima Local Meteorological Observatory (KMO), 10 km W from the crater, was 14 g/m2.

On 14 December, bombs and lapilli were ejected and deposited on the flanks. A small quantity of ashfall was observed at Aburatsu and Miyako-no-jo. During the eruption, 14 lightning strikes occurred during a 10-second interval. January's only eruption produced <1 g/m2 of ashfall at KMO.

Relatively quiet but an 11 May explosion sent bombs hundreds of meters down the flanks

During February-May 1997, the volcano was relatively quiet with occasional small explosions and B-type earthquakes; during March and April, seismic activity was moderate. On 11 May, an explosion of much smaller magnitude than the 14 December 1996 event (BGVN 22:01) created a detectable air-shock and projected bombs 40% of the way down the volcano's slope. The Sakurajima Volcanological Observatory reported increasing A-type earthquakes for a few months before the explosion.

A 4 February report stated that Sakura-jima was relatively quiet throughout most of 1997. According to the Japan Meteorological Agency (JMA), 4,466 tremors occurred in 1997, the lowest annual total since 1965. The total number of 1997 explosions was 35; the record low was set in 1971 when only 10 explosions occurred.

Activity increased during December 1997-January 1998. During December, eight explosions were observed; during 1-27 January there were ten. According to the Sakurajima Volcanological Observatory (SVO), type-A and type-B earthquake counts were relatively high both months.

A 3 December 1997 explosion issued at least 70,000 tons of ash, the estimated mass of fallout on Sakura-jima island. According to a volcanic ash advisory issued to aviators by the Tokyo Volcanic Ash Advisory Center, the eruption occurred at 1055 and sent ash up to ~3 km. The ash cloud extended 25 km S and 50 km E.

A 24 January 1998 ash advisory reported an eruption at 1750 and ash drifting SE at a height of ~1 km. A ground-based observer reported an ash plume that extended 10 km SE at 2000. Due to cloud cover in the area, ash was not seen on satellite images.

Sakura-jima produced frequent explosions in December 1997-January 1998 (BGVN 23:01). A 20 January volcanic ash advisory reported an eruption at 1227. An 8 February advisory reported an eruption at 0420; the volcanic ash cloud reached ~2.1 km altitude and drifted SE. A notice later in the day reported another eruption at 0508 with an ash cloud at ~2.1 km altitude extending SE. A 16 February advisory reported an eruption on 15 February that sent a plume to the E at ~18 km altitude. Observers in Kagoshima Airport saw a volcanic ash cloud to the SE and S at 0600 on 16 February. Satellite images did not show a plume due to the presence of low weather clouds. A 24 February ash advisory noted an eruption at 0705; volcanic ash extended E at ~18 km altitude.

In accord with ongoing eruptions, careful monitoring, and close communication with aviators, frequent notices of activity at Sakura-jima were released during March-May. According to various advisories, an eruption at 0130 on 2 March sent ash to ~1.8 km where it drifted 20 km S; an eruption at 0816 on 24 March sent ash to ~1.8 km where it drifted SE; and an eruption at 0505 on 5 April sent ash to ~2.0 km where it drifted N. An advisory noted an eruption at 0253 on 13 April but no ash cloud information was reported.

A Japan Meteorological Agency (JMA) volcanic advisory on 19 May stated that a swarm of volcanic earthquakes started at about 1700; in the following 4 hours, approximately 220 earthquakes were recorded. Daily earthquake counts were 334 on 19 May and 41 on 20 May. During 20-21 May, the volcano produced ten eruptions, nine of which were explosive. JMA scientists warned that the volcano's activity might increase following the swarm. As of 21 May, 49 explosions had occurred at Sakura-jima in 1998.

The following summarizes activity at Sakura-jima during January-June 1998 and January-May 1999. Information concerning events in 1998 were provided through communications from Yosihiro Sawada forwarded by Dan Shackelford. More recent information is available at the Japanese Meteorological Agency website.

The amount of tephra deposited around the volcano peaked during 1991-92 (up to 5.8 x 106 tons/month) but has since decreased; present deposits are <3 x 105 tons/month.

Activity during January-June 1998. Ten explosions and eruptions were recorded in January 1998. One explosion, on 7 January, produced a plume that rose 1,200 m above the summit. An explosive outburst on 24 January produced a column of incandescent ejecta accompanied by volcanic lightning. The total ashfall measured at Kagoshima Local Meteorological Observatory (KLMO) during January amounted to 10 g/m2.

Silent ash emissions (eruptions without explosions) occurred on 8, 16, 25, and 27 February 1998. A plume on 16 February rose 1,400 m above the crater. In March 1998, 22 eruptions (without explosions) were recorded. Eruption plumes on 2 and 3 March rose 1,200 m. KLMO recorded 37 g/m2 of ash for March. In April 1998, there were 19 eruptions, including eight explosions. The highest plume during April was observed 1,500 m above the crater on 30 April. April ashfall totaled only 1 g/m2.

Forty-one eruptions were observed in May 1998, including 27 explosive eruptions. The highest plume observed rose 2,500 m above crater on 24 May. A volcanic earthquake swarm lasted seven hours on 19-20 May. The total May ashfall was 105 g/m2. All five eruptions recorded during June were explosive. On 6 June an eruption plume rose 1,100 m above the crater. The total June ashfall deposit was 5 g/m2 thick.

Activity during January-May 1999. January 1999 was characterized by a low level of volcanic earthquakes, although 13 eruptions occurred. During February-April 1999 observers recorded 44 eruptions, including 15 explosions. Eruptive activity was relatively high during 11-16 March when there were 10 eruptions, including eight explosions. An eruption column rose 1,800 m on 20 April.

Sakura-jima volcano had a heightened level of eruptive activity during the period 28 July-12 August. Large eruptions occurred at 2022 on 30 July, at 2216 on 1 August, and at 0030 on 2 August when ballistic ejecta fell as far away as the mid-flank of the volcano. The activity level reduced after 13 August; only one-fifth of the number of explosions occurred during following 10 days. As of 23 August, 78 explosions had occurred during 1999.

The southern-most cone at Sakura-jima, Minami-dake, manifested increased eruptivity from late October to early November 1999. Following a lull in the second half of November, vigorous activity in December was marked by incandescent columns, large amounts of bomb ejections, and ballistics falling as far as 4 km from the crater.

High eruptive activity occurred in late October and early November 1999. On 31 October the JMA issued a Volcanic Advisory. In early November, 19 eruptions (including 18 explosions) occurred at Minami-dake before activity declined to lower levels later in the month. Activity increased again in early December with a few explosions each day and small numbers of ballistic clasts falling onto the upper slopes. On the afternoon of 10 December JMA issued another Volcanic Advisory. At 0555 this day, Sakura-jima issued a large amount of bombs. Incandescent columns as high as 100 m were accompanied 116 times by volcanic lightning. According to a JMA field inspection, ballistics were scattered 3-4 km away from the Minami-dake crater; the maximum size was 4 cm across. Incandescent columns rose as high as 300 m at 0554 on 24 December and were accompanied by volcanic lightning six times.

Daily numbers of eruptions ranged from 2 to 8 during early- to mid-December; eruptions were mostly explosive. The maximum amplitude of explosion earthquakes recorded at JMA observation point A, 4.6-km WNW of the crater, reached up to 28 µm; the largest value was caused by an explosion at 1301 on 12 December. The plume heights of December explosions ranged from 1,500 m to 2,000 m. Explosions took place on 23 consecutive days between 3 and 25 December. This is the longest record of daily explosions since JMA started observing Sakura-jima in 1955; the previous record was 21 days in 1960. Explosions began again late in the month, with six more on 31 December.

The total of 88 explosions during December 1999 was the second highest monthly count since 1955; the highest was 93 explosions in June 1974. According to the JMA, the total number of eruptions in 1999 was 386, including 237 explosions.

Frequent explosive eruptions continued in early January (figure 21). Explosions on 2 January sent an eruption column to 2,200 m above the crater rim and emitted abundant cinders, as well as bombs that fell midway down the flanks of the volcano. Nine explosive eruptions occurred on 5 January, one of which again ejected cinders and bombs as far as the middle flank of the volcano. The highest plumes in early January reached 2,200 m above the crater rim during explosions at 0821 on 5 January and at 0746 on 14 January. The maximum amplitude of explosion seismic signals at JMA observation point A (4.6 km WNW of the active crater) was 17 µm for the 0513 explosion on 14 January.

Figure 21. Eruption at Sakura-jima at 0900 on 8 January 2000 from 3.5 km SW of the Minami-dake crater. Courtesy of Tatsuro Chiba.

According to observation reports by the Japan Meteorological Agency (JMA), Minami-dake, the southernmost crater of Sakura-jima, erupted at 1642 on 7 October, marking the 132nd explosion this year. The eruption column reached 5 km above the crater, and was accompanied by volcanic lightning 18 times. The maximum amplitude of the earthquake associated with the explosion was 4 µm at the JMA observation point 4.6 km WNW of Minami-dake. Abundant ash fell over the central and northern sections of Kagoshima. Lapilli with a maximum size of 3 cm fell on the NW portion of the island, breaking 35 car windshields.

A pilot en route from Guam to Fukuoka received a dispatch warning of a major ash cloud in the flight path. The pilot saw the cloud clearly at a distance of 80 km from Sakura-jima and noted a small white plume over the summit. The pilot also observed a brown-red cloud downwind and SE of the volcano at an altitude of 2.5 km. As the aircraft approached, the plume grew suddenly larger and became dark gray during an eruption of ~30-45 seconds duration. The pilot deviated 19 km to the W while descending and flew past the cloud at an altitude of 5.5 km. After passing safely, the pilot observed the ash cloud diffusing ~100 km downwind at an altitude level with the summit. This incident highlights the importance of efficient information relay from field observers through a dispatch to pilots in order to avoid potentially hazardous in-flight ash encounters. As of 17 October no distinct changes in activity at Sakura-jima have been observed, although a small number of volcanic earthquakes have occurred.

Reference. Casadevall, T.J., 1994, Volcanic ash and aviation safety: Proceedings of the First International Symposium on Volcanic Ash and Aviation Safety: U.S. Geological Survey Bulletin 2047.

An observer at Kagoshima Airport reported seeing an ash cloud from Sakura-jima at 0900 on 22 July 2002 that rose to 2.1-2.4 km altitude. An ash plume was visible on satellite imagery at 1052 (0152 UTC) that day extending to the SW.

A photograph taken by the webcam at ttp://yumemaru.com/s/ shows a plume of undetermined composition originating from the island on 17 April 2003 (figure 22). This type of event is common at Sakura-jima.

Figure 22. Photograph of Sakura-jima taken on 17 April 2003 showing a plume originating from the island. Courtesy of Yunemaru.

Based on information from the Japanese Meteorological Agency (JMA), the Tokyo Volcanic Ash Advisory Center (VAAC) reported that on 3 December 2003 at 2025 ash was emitted from Sakura-jima, rose to ~2.5 km a.s.l., and extended to the S. An eruption on 12 January 2004 at ~1430 produced an ash cloud that rose higher than 2 km altitude. On 19 and 20 February, explosions produced ash clouds that rose to unknown heights. No ash was visible on satellite imagery. Based on JMA information, the Tokyo VAAC reported that explosions on 26 March at 1715 and 27 March at 0607 produced plumes that extended S and rose to ~2.5 km and ~2 km altitude, respectively.

An eruption on 17 April produced a gas-and-ash plume that rose to ~3 km altitude and extended W. Another eruption on 25 April produced an ash plume that rose to ~2.4 km altitude. and extended N. The Tokyo VAAC reported, based on information from the JMA, that an eruption occurred on 28 April at 1820. It produced a plume that rose to ~2.4 km altitude and drifted SE. No ash was visible on satellite imagery.

According to the Har-Tass news agency, JMA reported a powerful ash-bearing discharge on 15 May at 1107. Specialists stated that the activity was the most intensive in four years. There were no reports of damage or injuries. The explosion registered as 'large' on the JMA's scale for both the sound and the strength of the tremor it caused, according to a quoted official at the local agency office in Kagoshima.

The Tokyo VAAC said the ash plume rose to more than 1.8 km altitude. An explosion occurred on 17 May at 1946, sending an ash plume to a height of 2.1 km altitude. On 18 May a pilot reported ash at a height of ~1.2 km altitude and ~23 km S of the Amori region. During 19-24 May, several explosions produced ash clouds. The highest reported ash cloud reached ~2.4 km altitude on 24 May. An explosion on 20 June at 1523 produced an ash cloud that rose to an unknown height.

According to Yukio Hayakawa, on 4 June 2006 Sakura-jima erupted. The vent, which was outside the summit crater, was near or within the crater which issued the 1946 (Showa) lava flow, on the E slope of Minami-dake summit. The eruption continued intermittently until the next morning. A small amount of ash fell in Kagoshima city. In the following days it became calm.

On 10 June, the Sakura-jima Volcano Research Center reported an increase in low-frequency earthquakes since mid-March and in small tremors with a less than 2 minute duration since mid-May 2006. A thermal anomaly at the volcano grew in size after February 2006.

This was the first reported Sakura-jima eruption from a vent outside the summit crater in 58 years. The 1946 vent was the source of major lava flows that reached the E and S coasts of the former island.

According to the Sakurajima Volcano Research Center (SVRC) at Kyoto University, an eruption started on 4 June 2006 at the Showa crater, a spot that differs from vents active in recent decades at the summit of Minami-dake ("south mountain"; BGVN 31:06 and many previous reports). The Showa crater resides on the E slope of Minami-dake at an elevation of ~ 800 m (figures 23, 24, and 25). Showa crater was formed in a 1946 eruption; the 1946 vent was the source of lava flows that spread E and then branched to travel S and ENE (figure 25).

Figure 24. A sketch map focused on the geologic context of Sakura-jima, the Aira caldera, and adjacent calderas. The Kagoshima graben forms the Bay of the same name. The graben also lies coincident with several caldera margins. Sakura-jima resides at the S portion of Aira caldera. Modified slightly from Okuno and others (1998).

Figure 25. A geological map of Sakura-jima shown with several key features and eruptive dates labeled. Topographic highs from N to S include Kita-dake (K), Nika-dake (N), and Minami-dake (M). Craters at the summit of Minami-dake have been the active in past decades, but the eruption that started on 4 June eruption vented at Showa crater (S). An E flank lava flow (the Taisho Lava of 1914-1915) joined what had been an island's SE side to the shore (arrow at lower right labeled "j" aims at the zone of contact). Fringing the roughly circular former island are several areas of submarine volcanic and intrusive deposits (labeled here with the abbreviation "subm."). For example, the large area budding NE from the island consists of submarine and intrusive rocks of 1779-1780. Many of the Holocene eruptive deposits are dacites and andesites. They commonly bear pyroxene (and also sometimes, olivine). Besides lava flows, deposits include welded air-fall and pyroclastic-flow deposits (in some cases showing rheomorphosed textures indicative of movement downslope after forming a welded mass). From the Geologic Survey of Japan, AIST website (after Fukuyama and Ono, 1981 and Kobayashi, 1988).

Unfortunately, at press time many details still remained unavailable to Bulletin editors regarding the duration and character of the return of venting at Showa crater. It is also unclear to what extent the Minami-dake summit craters continued to participate in the emissions.

The 4 June 2006 eruption continued intermittently, including an evening eruption on 7 June which sent an ash column ~ 1 km above the crater. Figure 26 shows one such eruption on 6 June.

Figure 26. A photograph of Sakura-jima erupting at 1231 on 6 June 2006 from Showa crater. Courtesy of SVRC, Disaster Prevention Research Institute, Kyoto University.

A series of plots describe the short- and long-term seismicity and volume of magma supplied at Sakura-jima (figures 27 and 28). The number of shallow earthquakes had increased since the middle of March 2006 (figures 26 and 27), and small volcanic tremors with a duration shorter than 2 minutes had increased since the middle of May 2006. GPS data showed continued inflation in the N part of the Aira caldera, an observation attributed to incoming magma. Kazuhiro Ishihara, director of SVRC, commented that the present eruption was considered to be related to magma accumulating in the Aira caldera and searching for an exit.

Figure 28. Plot of the daily number of volcanic earthquakes at Sakura-jima for the period 1 January-7 June 2006. Courtesy of SVRC, Disaster Prevention Research Institute, Kyoto University.

Table 14 presents a chronology of ash-plume observations made since the previous Bulletin report (BGVN 31:06). The table is based primarily on reports from Tokyo Volcanic Ash Advisory Center (VAAC) and covers the interval 7 June 2006 to 20 March 2007. Most of the plumes described did not exceed 3 km altitude. The tallest plume recorded on the table, an ash plume on 20 March 2007, rose to 3.7 km altitude.

Table 14. Heights and drift of plumes and their character at Sakurajima from June 2006-March 2007. Some of the data during mid-June 2006 were previously reported, but new information has emerged. Courtesy of SVRC and Tokyo Volcanic Ash Advisory Center.

Date

Plume altitude/drift

Other observations

07-12 Jun 2006

3.4 km

--

10 Jun 2006

--

SVRC reported increase in low-frequency earthquakes since mid-March and in small tremors with a less than 2-minute duration since mid-May 2006; thermal anomaly at the volcano grew in size after February 2006.

14, 16, 19 Jun 2006

2.1 km

--

02 Aug 2006

2.4 km/SW

explosion

09 Aug 2006

2.4 km/straight up

eruption

22, 23, 26 Aug 2006

2.4 km/SW

eruptions

03-04 Sep 2006

2.7 km/NW and N

eruptions

06 Sep 2006

--

explosion generated eruption cloud

19 Sep 2006

3 km/straight up

eruption

20, 21 Sep 2006

2.4 km

eruptions

07, 08, 10 Oct 2006

1.8-2.4 km/W, S, and SW

eruptions

21 Oct 2006

3.4 km/straight up

explosions

25 and 27 Oct 2006

2.1-2.4 km/SW and NE

ash plumes

04-05 Nov 2006

2.1-2.4 km/NE, SE, E

eruptions

22 Nov 2006

2.1 km/W

explosions

26 Nov 2006

--

eruption

12 Dec 2006

2.1 km/NE

eruption

13 Dec 2006

--

explosion

02 Jan 2007

3.4 km/SW

eruption

10 Feb 2007

--

explosion

13 Feb 2007

2.1 km

explosion

15 Feb 2007

1.5 km

ash plume

20 Mar 2007

3.7 km

ash plume

Volcanic hazards research. Lee and others (2005) reported the successful remote measurement of significant amounts of ClO (as well as BrO and SO2) in a volcanic plume from Sakura-jima during May 2004. Near the volcano they also observed halogen-catalyzed, local surface ozone depletion. The investigators employed ground-based, multi-axis, differential optical absorption spectroscopy. Their results help document the presence of a wide range of chemical species that have potential health implications for populations living nearby.

The center of Kagoshima City (population ~ 550,000) sits ~ 10 km from Minami-dake's summit and ~ 4 km from Sakura-jima's E shore (just off figure 24, but along the trend of the arrow labeled KC). According to Durand and others (2001), "Since 1955 the city has been subjected to ashfall from Sakura-jima. Until 1990 ashfalls occurred up to twice per week, although this has decreased in frequency in recent years."

Durand and others (2001) comment that "[Kagoshima City] presents a good opportunity to study the impacts of volcanic ash on key services, or 'lifelines.' In addition, the city provides a chance to see how lifelines have been adapted to counter any problems presented by ashfalls." They also noted that, "The advice from Kagoshima would seem to be that during an ashfall event, people should bring in the washing and shut the doors and windows. People who have to go out and work in ashfall should wear goggles and a face mask. In Kagoshima, umbrellas are the only form of protection for many people going to work during ashfall events."

Our last reports on Sakura-jima (BGVN 31:06 and 32:04) discussed an eruption from Showa crater on 4 June 2006, the first eruption outside the summit crater since 1946. It also provided a chronology of plume observations between 7 June 2006 and 20 March 2007.

The current report continues the chronology of plume observations from 20 March 2007 to 24 April 2009 (table 15). Most of the plumes described since 20 March 2007 did not exceed 3 km altitude (figure 29). The tallest plume recorded on the table, an ash plume on 9 April 2009, rose to about 5 km altitude.

Table 15. Heights and drift of plumes and their character at Sakura-jima from 20 March 2007 to 24 April 2009. Courtesy of Tokyo Volcanic Ash Advisory Center, pilot reports, and the Japan Meteorological Agency (JMA). Times and dates are local.

Figure 29. Aerial photograph taken from the W of a plume from Sakura-jima's Showa crater as seen on 10 March 2009. Courtesy of JMA.

On 19 February 2009 JMA lowered the Alert Level from 3 to 2, because after the 1-5 February explosions, no eruptions had occurred either from Showa crater or Minamidake summit crater, seismicity was low, and no crustal deformation was observed (figure 30). As a result of heightened activity, the Alert Level was raised to 3 on 2 March, but dropped to 2 on 24 April 2009 due to low seismicity, lack of deformation, and absence of large eruptions. According to JMA, the shape of Showa crater has not changed recently, but the depth of the crater had increased. Photographs taken during an overflight on 10 March 2009 (figures 31 and 32) showed changes in morphology and temperature.

Figure 30. Sakura-jima tilt recorded at Arimura during February 2009. The vertical axis indicates the sense and magnitude of movement. Data from Osumi Kasen Kokudo (Japan's Ministry of Land, Infrastructure, Transport and Tourism). Courtesy of JMA.

Figure 31. A comparison of the morphology of Sakura-jima's Showa crater: (top) 28 July 2008, (bottom) 10 March 2009. Courtesy of JMA.

Figure 32. N-looking infrared photo of Sakura-jima's Showa crater on 10 March 2009. Scale at right shows the estimated temperature (°C). Note the high temperature in Showa crater. The crater rim at higher elevation (upper left) is called Minami-dake ("M" on the geologic map in the previous issue). Courtesy of JMA.

An article in Asahi newspaper contained several photos of the 9 April 2009 ashfall in Kagoshima City, about 10 W of Sakura-jima. This was the heaviest ashfall since October 2002.

During the last two years, the only thermal anomaly recorded by MODIS-MODVOLC for Sakura-jima was on 17 December 2008 (1 pixel).

Two recently published articles (citations below) describe the mechanism of explosive eruptions at Sakura-jima and two other Japanese volcanoes, and color measurements of Sakura-jima's ash deposits.

Our last reports on Sakura-jima (BGVN 31:06, 32:04, and 34:03) provided maps as well as a chronology of plume observations on this very active stratovolcano for the interval between 7 June 2006 and 24 April 2009. A small pyroclastic flow occurred on 9 April 2009.

The current report continues the chronology of plume observations from 3 May to 3 October 2009 (table 16). Most of the plumes described since 20 March 2007 did not exceed 3 km altitude. The tallest plume recorded in the table, an ash plume on 30 May 2009, rose to about 4.6 km altitude. The 3 October eruption from Minami-dake crater was described as violent. From 1 January through 30 September 2009, no thermal alerts were recorded by MODVOLC.

Table 16. Heights and drift of plumes and their character at Sakura-jima from 3 May 2009 to 29 September 2009. Courtesy of Tokyo Volcanic Ash Advisory Center, pilot reports, and the Japan Meteorological Agency (JMA). Dates are local.

Late 2009 activity. According to JMA, Sakura-jima exploded violently from the Minami-dake crater at 1645 on 3 October 2009. The resulting Vulcanian plume rose up to 3 km above the crater and ballistics reached as far as 1.7 km away from the crater. This explosive eruption was the first from Minami-dake crater since 22 February 2009. The Showa crater was also active on the night of 2-3 October. Several explosions were observed then, and red hot materials were ejected up to 800 m from the rim.

Our last report covered the explosive eruptions of 2-3 October 2009 from two of Sakura-jima's active vents: Minami-dake and Showa (BGVN 34:08) (figure 33). Minami-dake was last active on 22 February 2009. This report covers Sakura-jima's activity from October 2009 through October 2011; datasets may have various termination dates due to availability.

Figure 33. Location of Sakura-jima; surrounded by Kagoshima Bay and connected to the mainland of Kyushu, Japan by lava flows from 1914 AD (SW side of the island). Satellite image courtesy of Japan Aerospace Exploration Agency (JAXA) and index map from MapsOf.net.

The ash plumes of October 2009 to October 2011 reported by the Tokyo Volcanic Ash Advisory Center (VAAC) were disclosed in pilot's reports and satellite observations. Plume heights had a maximum altitude range of 1.2 to 4.9 km. VAAC released regular advisories during this time period, often more than once each week.

For the next 11 months following the explosive 2-3 October 2009 events, the Japan Meteorological Agency (JMA) maintained Alert Level 3 status due to intense eruptions from Showa crater (figure 34). The five-tier alert system used by JMA assigns red alert to Level 5; a Level 3 status forbids anyone to approach the volcano. Activity was occasionally Strombolian and Vulcanian during this time period. Lava fountaining on 8 February 2010 reached 1,000 m above the crater; this activity was visible at night and lightning was observed within the ash plume.

Figure 34. Plume heights and documented explosions for Sakura-jima's primary eruptive vents: Minami-dake (top) and Showa (bottom). Data is plotted for January 2009 through July 2011. Courtesy of JMA.

On 30 May 2010 an ash plume rose 2.8 km from Showa crater. A small pyroclastic flow was documented on the E flank (figure 35). A camera located at the Ohsumi National Office of Rivers and Highways recorded the vertical plume and pyroclastic flow with both visible and thermal images. The pyroclastic flow traveled ~ 700 m and had temperatures up to 500°C above the background levels.

Figure 35. An ash plume rose up to an altitude of 2.8 km from Sakura-jima's Showa crater and a pyroclastic flow traveled down the E flank. The eruption occurred at 1140 on 30 May 2010 and was captured by visual photography and a thermal camera. Courtesy of JMA.

Explosions were numerous in 2010 and according to JMA, by 20 June a new record had been reached; 550 explosions had already occurred at Sakura-jima. The Japan Times reported that the previous record high in a single year was 548 in 2009. By September 2010, this activity was less vigorous; the plumes from Showa crater were frequently less than 1 km high and no additional activity was reported from Minami-dake. On 30 September, JMA reduced the Alert Level but maintained warnings that no one should approach the summit craters. Earthquakes and tremor had become rare and constant deflation was recorded by tiltmeter and GPS. By June 2010, the long trend of inflation recorded by the water-tube tiltmeter at Arimura station peaked and in early July, abruptly began measuring deflation (figure 36).

Figure 36. Tilt change at Sakura-jima observed by the water-tube tiltmeter at Arimura station from January 2009 to September 2011. Tidal response was corrected and inflation at the summit corresponds to positive tilt. In the bottom panel, the red bars denote monthly frequencies of explosions from Showa crater. Courtesy of JMA.

From 7 to 20 October 2010, explosive eruptions became more frequent and exceeded background levels from the previous month. A large explosion on 13 October produced ejecta that reached ~ 1.3 km from Showa crater. Earthquake activity was consistently low, but elevated levels of tremor were recorded prompting JMA to raise the Alert Level to 3. During the subsequent months, explosive, ash-rich plumes became more frequent, increasing from 59 in November, and 62 in December, to 102 in January.

Activity was concentrated within the Showa crater until February 2011 when renewed activity began simultaneously at Minami-dake. Last active on 3 October 2009, the summit crater of Minami-dake released two ash-rich plumes on 7 February 2011. Volcanic bombs from Showa crater landed 0.8-1.3 km from the crater. At 1908 on 19 February, a pyroclastic flow extended ~ 500 m down the SE flank. JMA recorded 144 explosions that month, 110 of these events produced ash.

Incandescence and pyroclastic flows from Showa crater. Explosive eruptions continued at a lower rate during the following months; observers however, noted incandescence from Sakura-jima's summit from March through September 2011. An explosive eruption at 2242 on 30 April was recorded from Showa crater and was accompanied by a pyroclastic flow that extended 600 m from the crater on the E flank. Smaller pyroclastic flows 200-400 m in length occurred on 5 June, 12 July, and 1 and 12 September. These events traveled E and SE from the Showa crater and were recorded by thermal cameras and observers.

Aerial surveillance. Aerial observations of Showa crater were made on 31 May 2011 by JMA in cooperation with the Japan Maritime Self Defense Force (JMSDF). Fresh lava was discovered covering part of the crater floor with a diameter of 50-60 m (figure 37). Thermal results determined that the hottest area was in the center of the lava with temperatures up to 500°C above the measured background.

Figure 37. Sakura-jima's Showa crater on 31 May 2011. Aerial observations (A) and thermal imaging (B) determined the presence of new lava (appears black in plain light but has a high thermal output). Courtesy of JMA-JMSDF.

During the 31 May overflight, two ponds of water were identified within the Minami-dake vent. Both craters, A and B, contained water (figure 38) that persisted through 11 July, and by August the volume of water appeared to have increased in crater A. Observations from an aerial survey on 30 August found the ponds differed in color: Crater A appeared light blue, and Crater B was red-brown. There was no apparent change in the amount of degassing from these craters.

Figure 38. Sakura-jima's Minami-dake vent on 31 May and 11 July 2011. Aerial observations determined that water was collecting in craters A and B. Activity had not been recorded from this site since 7 February 2011. Courtesy of JMA-JMSDF.

This report provides highlights of activity at Sakura-jima during November 2011-July 2012 (following the previous report in BGVN 36:10). Over this interval, activity was characterized by consistent explosive eruptions that generated many plumes. Inflation of the edifice occurred over the first few months of the reporting period. Information was provided by the Japan Meteorological Agency (JMA) and the Tokyo Volcanic Ash Advisory Center (VAAC), unless otherwise noted. This report concludes with recently published research on the health consequences of exposure to ash erupted from Sakura-jima.

November 2011-July 2012. The reporting interval of the previous Bulletin report ended in a period of deflation of Sakura-jima’s edifice (BGVN 36:10, covering through October 2011). Coincidentally, JMA reported that Sakura-jima entered a period of inflation around the beginning of November 2011 (figure 39). That same episode of inflation continued through late January 2012, after which tilt measurements indicated little change through July.

Figure 39. Explosions (number per month, top) and tilt measurements (microradians - ?rad, bottom) at Sakura-jima during January 2009-July 2012. During November 2011-July 2012, explosions occurred more than 50 times per month, and the volcano was inflating until late January 2012 (pale orange area), after which little deformation was measured on tiltmeters (pale green area). Courtesy of JMA.

JMA reported that explosive eruptions occurred on average at a rate of more than two explosions per day (figure 39) during November 2011-July 2012. Explosions from Showa Crater commonly ejected tephra and/or ballistics up to 1.3 km from the crater. Plumes were reported to have risen 1-3 km above sea level (a.s.l.) by JMA and Tokyo VAAC more often than weekly; occasional plumes rose to 4 km a.s.l, and on 22 and 24 June, plumes rose 6.1 km a.s.l. Many plumes may have been ash-bearing, but Tokyo VAAC does not report ash content unless citing a pilot report (usually about once a week at Sakura-jima during the reporting interval). Noted exceptions from the common eruptive behavior over this reporting interval are explosions which ejected tephra up to 2 and 1.8 km from Showa Crater on 12 March and during 18-21 May 2012, respectively, and an explosion from Minami-dake Crater on 24 July that ejected ash up to 1.7 km from the crater. Pyroclastic flows travelled 200-300 m down the flanks of Showa Crater on 21 May and between 4 and 8 June.

Richard Roscoe, a visitor to the volcano, photographed Showa Crater in April 2012, and noted that it was ~20% wider in the N-S direction as compared with early 2010 (figure 40).

Figure 40. A photograph of Sakura-jima’s Showa Crater taken in early April 2012, looking W. Richard Roscoe, the photographer, noted that the crater was ~20 % wider in the N-S direction than it was in early 2010. Courtesy of Richard Roscoe, Photo Volcanica.

Health effects of Sakura-jima ash. Hillman and others (2012) characterized ash from Sakura-jima and possible health concerns due to exposure to the ash; they primarily sampled recently erupted ash, but also sampled older units up to ~500 years old (from 1914 and 1471-1476 A.D.) to assess possible health concerns in the event that Sakura-jima returns to previous eruptive styles, including Plinian explosive eruptions. Their analyses aimed to, among others, measure the amount of cristobalite (a silica polymorph known to cause respiratory diseases) in the ash, characterize the grain morphology of ash particles, assess the surface reactivity of the particles, and test the potential of ash particles to cause hemolysis ? the rupturing of red blood cell membranes.

From their work, Hillman and others (2012) reported that all analyzed samples contained low concentrations of cristobalite compared to explosively generated ash at other volcanoes, and other silica polymorphs (quartz and tridymite) were not found. While a greater percentage of respirable ash is often generated during Plinian eruptions, the authors reported the lowest concentrations of cristobalite in ash from Plinian eruptive phases at Sakura-jima.

Morphologically, the authors found many respirable grains adhered to other particles. They also found nano-scale fibers, but reported that they were not related to asbestos in composition or morphology, and were of too low concentration to pose a respiratory hazard.

The surface reactivity of ash particles was reported to be low compared to other volcanoes, and Hillman and others (2012) concluded that “iron related reactivity, as a mechanism for disease, is unlikely at Sakura-jima volcano.” They also reported that ash particles had a low-to-mild potential of causing hemolysis. They concluded that ash from Sakura-jima does not have a high potential of causing respiratory disease via the mechanisms studied, but stated that other potential sources of toxicity needed to be analyzed.

This report summarizes activity at Sakura-jima (a cone within the Aira caldera) between August 2012 and December 2013. Data were largely provided by the Japan Meteorological Agency (JMA) and the Tokyo Volcanic Ash Advisory Center (VAAC). Monthly JMA reports of volcanic activity have been translated into English since October 2010. These reports can be viewed online (see reference section below).

Sakura-jima has been the subject of repeated reports here, many reporting recent explosions (BGVN 31:06, 36:10 and 37:05). Pepe and others (2013) remarked that at Sakura-jima, "Explosive eruptions of Vulcanian type, with ash emissions, have occurred intermittently from 1955 to 2002. From 2009 to December 2012, a strong and continuous period of volcanic activity has been recorded mainly at the Showa Crater producing plumes that reached altitudes of 1.8-3.5 km." JMA (2013) commented that resumption of eruptions at the Showa crater in June 2006 marked a return of activity at this vent after 58 years. It is also noteworthy that during this reporting interval no multi-week-long break in eruptions took place. In other words, the eruptions discussed below all took place within a larger a larger episode ongoing since 2006.

The locations of Sakura-jima and the nearby Kagoshima City are shown in figure 41. The city of Kagoshima sits 8 km W of the volcano and is home to over 600,000 residents. Sakura-jima has several craters, including the currently active Showa crater and the Minamidake crater (figures 42 and 43).

Figure 41. (Larger map) Main islands of Japan showing location of Sakura-jima. (Inset map) Sakurajima with respect to Kagoshima City. Revised from an original by Jim Markowich and Sandy Mayer.

Figure 43. Topographical map of the central crater area of Sakura-jima, showing relationship of Showa and Minamidake craters. Map was based on 2010 aerial laser measurement (LIDAR) data. Courtesy of the Japanese Ministry of Ministry of Land, Infrastructure, Transport and Tourism, Osumi Office of River and National Highway (Kyushu Regional Development Bureau).

According to JMA, during this reporting interval (August 2012 to December 2013) eruptive activity at Showa crater remained high and volcanic seismicity remained relatively low (table 17). Earthquake hypocenters were located at depths ranging from 0-4 km below sea level under the volcano. The average sulfur dioxide fluxes taken during JMA field surveys were relatively high (800-4,100 metric tons/day, table 17).

Table 17. For the interval August 2012-December 2013 numerous eruptive events, including explosions, took place without significant hiatus. The number of eruptions, earthquakes, and tremor, and average sulfur dioxide fluxes measured monthly. "Total eruptions" include the explosive eruptions. Average SO2 levels are based upon 1-4 field surveys per month. Data compiled from JMA monthly reports. NR means not reported.

Month

Total eruptions

Explosive eruptions

Number of earthquakes

Tremor

Average SO2 level (t/d)

August 2012

59

43

370

270

2,600-3,300

September

73

48

349

283

2,700-3,700

October

61

35

736

500

2,100-5,700

November

71

55

635

363

2,100-2,200

December

55

43

813

453

1,200-1,400

January 2013

124

96

1,058

230

1,700-4,100

February

132

119

746

321

800-1,900

March

74

61

552

321

2,800

April

17

14

287

56

1,600-2,300

May

70

58

NR

NR

2100-3400

June

18

17

NR

NR

2200

July

128

83

NR

NR

1,600-2,200

August

144

118

NR

NR

1,400

September

154

110

NR

NR

2,200-2,900

October

127

87

NR

NR

900-2500

November

69

50

NR

NR

900-1,500

December

40

22

NR

NR

1,700-1,800

Showa crater had frequent explosions that commonly ejected tephra and/or ballistics up to 1.3-1.8 km from the crater, according to JMA reports. During explosive eruptions from August 2012 through July 2013, ash plumes rose to a maximum height of 2 to 3.5 km above the crater rim. From August through November 2013, the maximum heights ranged from 4 to 5 km. The Tokyo VAAC issued numerous advisories during this reporting period. Occasionally, incandescence was observed at night with high-sensitivity cameras, and infrequently with the naked eye.

On 7 October 2012, a very small pyroclastic flow was observed for the first time since 6 June 2012; it flowed 300 m E. Small pyroclastic flows were also observed on 30 November and 26 December 2012, both of which flowed 500 m E. Very small pyroclastic flows were sporadically observed in 2013.

Table 18 shows the monthly ash fall measurements and the computed mass of ash falling in Kagoshima. The total amount of ashfall for 2012 was 6.6 million tons, compared to 4.5 million tons in 2011. The overall 2012 burden was the largest since the resumption of activity at Showa crater in 2006, As seen in table 18, during October 2013 an estimated 1 metric ton of ash fell on Kagoshima, the largest amount since the activity resumed at Showa crater in 2006.

Table 18. The mass of ash that fell on the city of Kagoshima during August 2012-December 2013. The measurements of density of ashfall burden were measured at the Kagoshima Local Meteorological Observatory (KLMO), 10 km W of Showa crater. The total estimated amount of ashfall on the City in millions of metric tons was estimated by the Kagoshima prefectural government. "NR" means not indicated in JMA monthly reports.

Month

Measurement at observatory (KLMO) (g/m2)

Total mass on City ( x 109 kg)

August 2012

142

0.34

September

194

0.4

October

153

0.3

November

137

0.5

December

13

0.5

January 2013

11

0.4

February

24

0.8

March

8

0.6

April

0.5

0.2

May

74

0.5

June

4

0.1

July

2

0.7

August

59

0.7

September

906

0.8

October

720

1.0

November

7

0.5

December

NR

NR

Larger explosions with greater effect occurred during August-November 2013. On 18 August 2013, an explosion produced a large plume that rose to 5 km above the crater rim and drifted NW (figure 44). According to a news account (Associated Press), the plume height was the highest since JMA starting keeping records in 2006. Ash fell over a wide area from Kagoshima City to Koshikijima Island (about 70 km WNW of Kagoshima City) in amounts large enough to cause suspension of public transportation in Kagoshima City (figure 45). The explosion produced a small pyroclastic flow that flowed about 1 km SE of Showa crater. This report quoted a Kagoshima official as saying that the 18 August explosion was Sakura-jima's 500th eruption that year.

Figure 44. Photo of Sakura-jima on 18 August 2013, taken from Kagoshima City, looking E. Courtesy of AP Photo/JMA's Kagoshima Local Meteorological Observatory. The plume rose to 5 km above the crater rim (or about 6 km in altitude).

Figure 45. E-looking view showing an ash plume from Sakura-jima on 18 August 2013 sweeping towards Kagoshima City. According to a news report (Associated Press), residents were urged to cover up and wear masks. Courtesy of AP Photo/Kyodo News.

On 29 August 2013, a large plume rose to 3 km above the crater rim and drifted ENE. Volcanic ash fell on an area from Sakura-jima Island to Miyazaki City (about 80 km NE of the volcano), and lapilli with a diameter of 1 cm fell on the Kurokamicho area of Kagoshima City (about 4 km E of Showa crater).

Another explosion on 4 September 2013 produced a relatively large plume that rose to 2.8 km above the crater rim and rapidly drifted S. Lapilli with diameters of up to 4 cm fell on small communities up to 3 km S of Showa crater, breaking the windows of more than ten cars and causing other damage. Smaller lapilli were found around Tarumizu City Hall (about 8 km SSE of the crater). A similar explosion on 25 September produced 2-cm lapilli that fell on another community about 3 km S of the crater, causing similar damage to car windows.

On 15 October 2013, lapilli with a diameter up to 3 cm fell on a community 3.5 km SW of Showa crater. Another explosion on 24 October resulted in 1-cm lapilli falling on a community about 5 km NW of the crater. Neither eruption caused any damage.

An explosion on 24 November 2013 produced a large plume that rose 4 km above the crater rim and drifted NE. Ash and 7-mm diameter lapilli fell on nearby communities. Lapilli with diameters of 1-1.5 cm also fell on a community 4 km SE of the crater on 18, 26, and 29 November.

Nearby Minamidake crater to the W of Showa crater was quiet during most months during the reporting period. According to JMA, Minamidake produced an occasional very small eruption beginning 20 October through the end of the year. In 2013, small eruptions were observed in January, August, November, and December.

Deformation. Pepe and others (2013) used satellite interferometry (InSAR) to create 44 interferograms for the years 2006-2012. They found the deformation complex, possibly the result of multiple inflation-deflation cycles. They stated, "The preliminary analysis of the mean deformation velocity reveals the presence of a consistent uplift signal in the North region of the Sakurajima Island that extends also to the North sector of Kagoshima bay. The corresponding deformation time series are characterized by a strong non-linear behavior. More specifically, the general uplift trend is found, interrupted by low amplitude subsidence phenomena. Finally, we argue that the complexity of detected deformation time series could be interpreted as the effect of cyclical periods of inflation and deflation."

Ground deformation measured with a water-tube tiltmeter installed 2.5 km SE of the Minamidake summit crater (by Japan's Ministry of Land, Infrastructure, Transport and Tourism, MLIT), found an almost static state after February 2012, changing around August 2012 to slight subsidence. During February 2013, this same instrument detected a slight uplift. Although other research groups deployed deformation instruments during this time, their data were not widely available.

In addition, JMA reported that an analysis of measurements of a satellite-based GNSS (Global Navigation Satellite System) suggested inflation around February 2013. In contrast, between July-December 2013, deformation was either almost negligible or slightly tended toward contraction.

Further background. More descriptive information is available in the National Catalog of the Active Volcanoes in Japan (JMA, 2013). The following extracts several key points from a much longer paragraph in that document. First, Sakurajima is an andesite-dacite composite volcano located on the southern rim of the Aira caldera. The SiO2 content of the rocks is between 56.5 and 67.2 wt %. Second, it is composed of two main cones-Kitadake and Minamidake-as well as numerous parasitic cones.

Sakurajima volcano at Aira caldera in southernmost Japan has records of historical eruptions back to the 8th century; it was very active in 2012 and 2013, and eruptive activity continued during 2014 with explosions and pyroclastic flows that have been ongoing since 1955. The Showa crater near the summit returned to activity in 2006 and has been the primary active vent since that time. The Japan Meteorological Agency (JMA) provides monthly reports on activity, and the Tokyo VAAC (Volcanic Ash Advisory Center) issued hundreds of reports about ash plumes during 2014.

JMA reported that Showa Crater erupted 471 times in 2014 (figure 46). This is less than half of the 1,097 eruptions reported for 2013, and is lower than average compared with the previous five years, but is also consistent with the periodic variation in eruptive frequency observed between 2009 and 2014 (figure 47).

Figure 46. Number of eruptions during 2014 from Showa Crater on Sakurajima volcano at Aira caldera. Data from JMA Monthly reports.

Figure 47. Number of monthly eruptions at Showa crater (red bars, top) on Sakurajima volcano at Aira caldera between 1 January 2009 and 31 January 2014. The lower graph represents the change in tilt observed with a water-tube tiltmeter at Arimura Station from January 2009 through January 2014 with tidal response eliminated. Inflation of the summit corresponds to positive tilts. Tilt values remained stable and changed little through 2014. Courtesy of JMA (Monthly Summary, January 2014).

Small pyroclastic flows that reached 400-600 m SE or E of Showa Crater were reported three times in 2014, on 22 January, 12 February, and 4 July. The Minamidake summit crater was generally quiet. Only one very small eruption was reported from it on 19 January, and a few very small eruptions were reported there in May. Incandescence was visible from the Showa crater, where virtually all the activity was focused, during several nights almost every week throughout the year.

Significant ashfall was reported by JMA for the 22 January eruption; the Central Fire Department of Kagoshima Fire Prevention Bureau reported that lapilli with a diameter of up to 1 cm fell on an area of Arimuracho in Kagoshima City (about 3 km S of the Showa crater) and larger lapilli with a diameter of 3 cm fell on the Arimura Observation Point (also about 3 km S of the Showa crater).

Most of the explosions during the year sent rocks to within 800 m of the Showa crater. Rocks were ejected as far as 1,300 m from the Showa crater in seven explosive eruptions in January, 12 times in February, 22 times in August, and eight times in October. Larger eruptions sent rocks even farther to distances up to 1,800 m from the crater on 9 March, twice in September, on 28 November, and on 8 and 11 December.

Ash plumes rising to an altitude of 2-3 km were reported weekly by Tokyo VAAC throughout the year. Most of the plumes drifted SE or S, but occasionally were observed drifting NE and other directions as well. Every month (except April) plumes also rose to heights of 3.7-4.6 km, and twice (in May and June) the highest plumes to 5.5 km were reported. A web camera in Tarumizu (12 km SE of Sakurajima) captured a typical ash plume on 24 October that rose to 4.6 km and drifted E (figure 48).

Figure 48. Image from an unspecified webcam in Tarumizu, 12 km SE of Aira's Sakurajima volcano, of an eruption at 1211 local time on 24 October 2014. The ash plume rose to 4.6 km altitude and drifted E. Image archived by and courtesy of Volcano Discovery.

This compilation of synonyms and subsidiary features may not be comprehensive. Features are organized into four major categories: Cones, Craters, Domes, and Thermal Features. Synonyms of features appear indented below the primary name. In some cases additional feature type, elevation, or location details are provided.

Cones

Feature Name

Feature Type

Elevation

Latitude

Longitude

Hirase

Cone

Nabeyama
Nabe-yama

Cone

Nakadake
Naka-dake

Stratovolcano

1110 m

Okise

Cone

Sakurajima
Sakura-zima
Sakura-jima

Stratovolcano

1117 m

31° 35' 33" N

130° 39' 32" E

Tagiri

Cone

Craters

Feature Name

Feature Type

Elevation

Latitude

Longitude

Aira

Pleistocene caldera

Kitadake
Mi-take
Kita-dake

Crater

1050 m

31° 35' 26" N

130° 39' 21" E

Minamidake
Minami-dake

Crater

850 m

31° 34' 46" N

130° 39' 38" E

Showa

Crater

800 m

31° 34' 44" N

130° 39' 54" E

Wakamiko

Pleistocene caldera

-77 m

31° 39' 48" N

130° 47' 54" E

Domes

Feature Name

Feature Type

Elevation

Latitude

Longitude

Furihatayama
Furihata-yama

Dome

Gongenyama
Gongen-yama

Dome

Harutayama
Haruta-yama

Dome

Hikinohira

Dome

565 m

Yunohira

Dome

376 m

Basic Data

Volcano Number

Last Known Eruption

Elevation

LatitudeLongitude

282080

2017 CE

1117 m / 3664 ft

31.593°N
130.657°E

Volcano Types

Caldera
Stratovolcano
Pyroclastic cone(s)
Lava dome(s)

Rock Types

MajorAndesite / Basaltic Andesite
Dacite
Rhyolite

Tectonic Setting

Subduction zoneContinental crust (> 25 km)

Population

Within 5 kmWithin 10 kmWithin 30 kmWithin 100 km

4,918
113,874
905,254
2,610,033

Geological Summary

The Aira caldera in the northern half of Kagoshima Bay contains the post-caldera Sakurajima volcano, one of Japan's most active. Eruption of the voluminous Ito pyroclastic flow accompanied formation of the 17 x 23 km caldera about 22,000 years ago. The smaller Wakamiko caldera was formed during the early Holocene in the NE corner of the Aira caldera, along with several post-caldera cones. The construction of Sakurajima began about 13,000 years ago on the southern rim of Aira caldera and built an island that was finally joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kitadake summit cone ended about 4850 years ago, after which eruptions took place at Minamidake. Frequent historical eruptions, recorded since the 8th century, have deposited ash on Kagoshima, one of Kyushu's largest cities, located across Kagoshima Bay only 8 km from the summit. The largest historical eruption took place during 1471-76.

References

The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography.

Deformation during 1995 - 1998 [Uplift; Observed by InSAR]

Start Date: 1995

Stop Date: 1998

Direction: Uplift

Method: InSAR

Magnitude: 2.000 cm

Spatial Extent: Unknown

Latitude: 32.000

Longitude: 131.000

Recorded differential JERS interferograms over the Aira Caldera encompassing the 1993?1998 period. (a) Interferogram spanning four years from June 1993 to March 1997. (b) Interferogram spanning five years from October 1993 to August 1998. (c) Interferogram spanning five years from October 1993 to September 1998. A complete cycle of phase (purple, blue yellow) represents a decrease in range of 11.73 cm between the ground surface and the satellite.

Emission History

There is no Emissions History data available for Aira.

Photo Gallery

An eruption plume from Sakura-jima, one of Japan's most active volcanoes, rises above the city of Kagoshima. Sakura-jima is a post-caldera volcano of the Aira caldera at the northern half of Kagoshima Bay. The construction of Sakura-jima beginning about 13,000 years ago built an island that was finally joined to the Osumi Peninsula during the eruption of 1914. Frequent historical eruptions, recorded since the 8th century, have deposited ash on Kagoshima, one of Kyushu's largest cities.

Photo courtesy of Richard Fiske (Smithsonian Institution).

A space shuttle photograph on October 6, 1985, shows a V-shaped eruption plume extending east from Sakura-jima volcano across the Osumi Peninsula to the Pacific Ocean. Sakura-jima volcano was constructed near the south rim of the 20-km-wide Aira caldera, which forms much of the northern end of Kagoshima Bay. The caldera was produced during an eruption about 22,000 years ago. Kagoshima City forms the lighter-colored area across the bay immediately west of Sakura-jima.

Sakura-jima entered a period of frequent intermittent moderate explosive eruptions in October 1955 that has continued until the present. Ashfall from the active vent at Minami-dake has often disrupted life at Kagoshima, southern Kyushu's largest city, located just 7 km across the bay. Ash plumes typically reach heights of 1-3 km above the vent. Mudflows and block ejection have intermittently affected populated areas on Sakura-jima island. This September 1981 view shows the erupting volcano from the west side of the island.

Copyrighted photo by Dick Stoiber, 1981 (Dartmouth College).

An ash-rich eruption column rises above a restaurant on Sakura-jima island in September 1981. Almost continuous explosive eruptions have been occurring at Sakura-jima since 1955. Residents on the island have learned to coexist with the volcano, which frequently dumps ash on residential areas. Occasional larger explosions have ejected ballastic blocks that have penetrated concrete roofs of buildings. Villages on Sakura-jima are located along the island's coast, but most are only 3-5 km from Minami-dake, the active summit crater.

Copyrighted photo by Dick Stoiber, 1981 (Dartmouth College).

An ash-rich eruption column rises above Sakura-jima on September 9, 1985. Almost continuous explosive activity has occurred at Sakura-jima, located at the southern end of the Japanese island of Kyushu, since October 1955. Eruption plumes typically rise 1-3 km above the vent, although occasional larger explosions occur. Ashfall commonly occurs over Sakura-jima island and periodically in Kagoshima City, 8 km to the west. Larger explosions eject ballastic blocks that have damaged structures on the island.

Photo by Tom Pierson, 1985 (U.S. Geological Survey).

An incandescent lava dome is visible in the Minami-dake crater of Sakura-jima in this September 9, 1981 aerial view. Sakurajima has been in almost continuous activity since 1955, producing frequent mild-to-moderate explosions that commonly produce ashfall on the island.

Photo by Norm Banks, 1981 (U.S. Geological Survey).

This torii, a Shinto shrine gate, was partially buried by pyroclastic-fall deposits from the 1914 eruption, leaving only the horizontal top beams exposed. The posts and chains surround the gate to protect this historical landmark. The torii, which originally was 3 m in height, was located at the village of Kurokami, on the east coast of Sakura-jima, 5 km from the summit.

Photo by Norm Banks, 1981 (U.S. Geological Survey).

A plume rises above the crater of Minami-dake (South Peak) on Sakura-jima volcano. Kita-dake (North Peak) lies at the right in this view from the SE. Activity at Kita-dake ended about 4850 years ago, after which eruptions took place at Minami-dake. Sakura-jima, one of Japan's most active volcanoes, is a post-caldera cone of the Aira caldera at the northern half of Kagoshima Bay. Frequent historical eruptions have deposited ash across the bay on Kagoshima, one of Kyushu's largest cities.

Affiliated Sites

The DECADE portal, still in the developmental stage, serves as an example of the proposed interoperability between The Smithsonian Institution's Global Volcanism Program, the MAGA Database, and the EarthChem Geochemical Portal. The Deep Earth Carbon Degassing (DECADE) initiative seeks to use new and established technologies to determine accurate global fluxes of volcanic CO2 to the atmosphere, but installing CO2 monitoring networks on 20 of the world's 150 most actively degassing volcanoes. The group uses related laboratory-based studies (direct gas sampling and analysis, melt inclusions) to provide new data for direct degassing of deep earth carbon to the atmosphere.

WOVOdat is a database of volcanic unrest; instrumentally and visually recorded changes in seismicity, ground deformation, gas emission, and other parameters from their normal baselines. It is sponsored by the World Organization of Volcano Observatories (WOVO) and presently hosted at the Earth Observatory of Singapore.

Middle InfraRed Observation of Volcanic Activity (MIROVA) is a near real time volcanic hot-spot detection system based on the analysis of MODIS (Moderate Resolution Imaging Spectroradiometer) data. In particular, MIROVA uses the Middle InfraRed Radiation (MIR), measured over target volcanoes, in order to detect, locate and measure the heat radiation sourced from volcanic activity.

Using infrared satellite Moderate Resolution Imaging Spectroradiometer (MODIS) data, scientists at the Hawai'i Institute of Geophysics and Planetology, University of Hawai'i, developed an automated system called MODVOLC to map thermal hot-spots in near real time. For each MODIS image, the algorithm automatically scans each 1 km pixel within it to check for high-temperature hot-spots. When one is found the date, time, location, and intensity are recorded. MODIS looks at every square km of the Earth every 48 hours, once during the day and once during the night, and the presence of two MODIS sensors in space allows at least four hot-spot observations every two days. Each day updated global maps are compiled to display the locations of all hot spots detected in the previous 24 hours. There is a drop-down list with volcano names which allow users to 'zoom-in' and examine the distribution of hot-spots at a variety of spatial scales.

EarthChem develops and maintains databases, software, and services that support the preservation, discovery, access and analysis of geochemical data, and facilitate their integration with the broad array of other available earth science parameters. EarthChem is operated by a joint team of disciplinary scientists, data scientists, data managers and information technology developers who are part of the NSF-funded data facility Integrated Earth Data Applications (IEDA). IEDA is a collaborative effort of EarthChem and the Marine Geoscience Data System (MGDS).